Surface disinfectant

Abstract

An antimicrobial aqueous liquid composition consisting of: (i) equal to or greater than 0.1% w / w of an antimicrobial fraction; (ii) equal to or less than 99.9% w / w water; (iii) 0 to 5% w / w diluents, excipients or carriers other than water, wherein the sum of the percentage amounts of (i), (ii) and (ii) is 100%, and wherein the total weight of the antimicrobial fraction in the composition consists of: (a) 60 to 70% w / w lactic acid or a water-soluble salt thereof; (b) 4 to 10% w / w citric acid or a water-soluble salt thereof; (c) 5 to 15% w / w anionic polycarboxylate surfactant; (d) 9 to 15% w / w α-Olefin (C12-C18) sulfonate; (e) 6 to 10% w / w anionic maleic acid co-polymer surfactant. Also claimed is a method of combating contamination of a site with a microorganism. The amounts of a-e present in the composition may be, respectively, 1.35-1.75 wt.%, 0.025 to 0.325 percent by weight, 0.05 to 0.5 % by weight 0.125 to 0.325 with the balance being water.

Description

The present invention relates to carboxylic acid based, quaternary ammonium compound free, antimicrobial aqueous liquid compositions with good residual efficacy, methods and kits for preparing the same and uses thereof to combat microorganisms. More specifically, there is provided an antimicrobial aqueous liquid composition comprising a specific carboxylic acid based antimicrobial fraction of defined components and relative amounts thereof which exerts persistent antimicrobial effects when applied to abiotic or biotic surfaces, even following repeated wet and dry abrasive wear at such surfaces, despite an absence of quaternary ammonium compounds. The compositions of the invention are expected to be essentially biodegradable following use and so should not accumulate in the environment. As shown in the Examples, even in a dilute form and despite an absence of quaternary ammonium compounds (QAC), the particular combination of components of the antimicrobial fraction of the composition of the invention, and their relative amounts, exert an antimicrobial effect that is residual (i.e. persistent or long-lasting) based on the industry standard PAS2424 screening test. Thus, the compositions of the invention have been shown to not only be able to exert a potent antimicrobial effect upon contact with the surface or site to which they are applied, but also are able to exert this effect beyond initial application and following abrasive wear over several hours thereby protecting the site or surface from subsequent recontamination or delaying the repopulation process. Moreover, the results disclosed herein suggest that the antimicrobial compositions of the invention may be applied by spray, atomiser or misting apparatus, or the like, or by the means of a fabric wipe or sponge impregnated with the composition, and have the same performance characteristics. When used in such dilute forms, the composition is expected to be biodegradable and so should not accumulate in the environment. The invention therefore also provides methods for combating contamination of a site with a microorganism, said method comprising contacting the site and / or the microorganism with the antimicrobial aqueous liquid composition of the invention, preferably by spray, atomiser or misting apparatus, or by the means of a fabric wipe or sponge impregnated with the composition. The site to be treated with the compositions of the invention may be abiotic or biotic, and in any context, and as such both medical and non-medical uses are provided. However, the properties of the composition of the invention make it particularly suited to use in the cleansing of hard surfaces in large scale industrial, agricultural, healthcare and commercial sites and domestic dwellings. Advantageously, the antimicrobial aqueous liquid composition of the invention may be provided in a concentrated form which may be diluted with an aqueous diluent at or near the site of application prior to use, thereby minimising the cost and environmental impact of the composition itself and all parts of the production and supply chain. That the antimicrobial aqueous liquid composition of the invention achieves this level of performance whilst being free of quaternary ammonium compounds, which have issues relating to microbial resistance, environmental accumulation and toxicity to higher organisms, is especially advantageous because it means the compositions of the invention should be essentially biodegradable and non-toxic following use. There is a continuing need to develop effective non-toxic surface disinfectants that have the least impact on the environment as possible and which do not contribute to the development of antimicrobial resistance. Such compositions must therefore be highly effective (possess high efficacy) so as to minimise the concentrations at which the of antimicrobial compound(s) (and any diluent or excipients) applied, and not only show antimicrobial activity when first used on or applied to a particular site, but for these effects to persist over several hours, especially following repeated cycles of wet and dry abrasive wear - so called residual efficacy - so as to minimise the number of reapplications required to maintain protection against recontamination. Even where the composition is water-based there is now pressure to minimise the use of this natural resource as much as possible, and so the surface disinfectants of the future must also display these properties when applied in small volumes, e.g. in droplet form from a spray, atomiser or misting apparatus or by fabric wipe. The antimicrobial compound(s) (and other ingredients) of such disinfectants must achieve these stringent performance requirements whist being non-hazardous to higher organisms or the environment and without accumulating in the environment whilst being following use. Moreover, the non-accumulating, nontoxic antimicrobial compound(s) (and other ingredients) of such disinfectants selected to achieve these performance requirements must also be those which do not contribute to the development of antimicrobial resistance, in particular quaternary ammonium compounds (QACs) should be absent from the formulation. The PAS 2424:2014 test method is a standardised testing protocol used in the UK and Europe to assess residual antimicrobial activity of hard surface disinfectants. There are known antimicrobial compositions with residual efficacy lasting for prolonged periods (e.g. up to 24 hours) that have passed such tests. However, all of these use QACs as active ingredients. QACs are often used due to their stability and convenience, but they have many drawbacks associated with them. These include, inter alia, accumulation in the environment, potential toxicity to higher organisms, e.g. at accumulated levels, and risk of antimicrobial resistance to QACs which would ultimately negate their effects and create difficulties in tackling microbial spores. To date, there has not been provided an non-toxic, nonaccumulating antimicrobial aqueous liquid composition which passes the PAS2424:2014 test for residual efficacy, whilst being entirely free from QACs. It is therefore an object of the present invention to provide an antimicrobial composition showing satisfactory residual efficacy (i.e. pass the PAS2424:2014 test), whilst being entirely free from QACs. In other objects the composition should be substantially non-toxic to higher organisms and should not accumulate substantially in the environment following use. In a further object the composition will be substantially biodegradable. In a first aspect, there is provided an antimicrobial aqueous liquid composition consisting of (i) equal to or greater than about 0.1 % w / w of an antimicrobial fraction consisting of Components (a) to (e) (ii) equal to or less than about 99.9% w / w water, and (iii) 0 to about 5% w / w diluents, excipients or carriers other than water, wherein the sum of the percentage amounts of (i), (ii) and (ii) is 100%, and wherein the total weight of the antimicrobial fraction in the composition consists of (a) about 60 to about 70% w / w lactic acid or a water-soluble salt thereof (b) about 4 to about 10% w / w citric acid or a water-soluble salt thereof (c) about 5 to about 15% w / w anionic polycarboxylate surfactant (d) about 9 to about 15% w / w a-Olefin (C12-C18) sulfonate (e) about 6 to about 10% w / w anionic maleic acid co-polymer surfactant. In accordance with the first aspect, Component (a) of the composition is lactic acid or a water-soluble salt thereof. Lactic acid (CAS 79-33-4) is an organic acid having the chemical formula CH3CH(OH)COOH. Any isomeric form of lactic acid or mixture thereof, e.g. racemic, may be used in the composition of the invention. In certain embodiments the L(+) isomer only is used, e.g. L(+) lactic acid. Component (a) is present in the antimicrobial fraction of the composition of the invention in an amount from about 60 to about 70% w / w, e.g. about 61 %, 62%, 63%, 64%, 65%, 66%, 67%, 68%, 69%, to about 70%, or about 60% to about 61%, 62%, 63%, 64%, 65%, 66%, 67%, 68%, 69% w / w. Any ranges of percentage w / w which may be formed from the combination of the aforementioned upper and lower endpoints are specifically contemplated. Thus, in some embodiments, Component (a) A is present in the antimicrobial fraction of the composition in an amount of about 60% w / w, 61 % w / w, 62% w / w, 63% w / w, 64% w / w, 65% w / w, 66% w / w, 67% w / w, 68% w / w, 69% w / w, or about 70% w / w. Preferably, Component (a) is present in the in the antimicrobial fraction of the composition in an amount of about 64% w / w, e.g. from about 63% w / w to about 65% w / w, or about 64 % w / w to about 65% w / w. In other embodiments Component (a) is present in the in the antimicrobial fraction of the composition in an amount of about 64.37 %, e.g. from about 64.32% w / w to about 64.42% w / w. Lactic acid is widely available from commercial suppliers, e.g. Jungbunzlauer. Other suppliers (or the supplier's approved distributors) are listed on the European Chemicals Agency (ECHA) Article 95 List of Approved substances and suppliers under the Biocidal Products Regulation. In accordance with the first aspect, Component (b) of the composition is citric acid or a water-soluble salt thereof. Citric acid (CAS 77-92-9) is an organic acid with the chemical formula HOC(CO2H)(CH2CO2H)2. Component (b) is present in the antimicrobial fraction of the composition of the invention in an amount from about 4 to about 10% w / w, e.g. about 4.5, 5, 5.5, 6, 6.5, 7, 7.5, 8, 8.5, 9, or 9.5% to about 10% w,w, or about 4% to about 5, 5, 5.5, 6, 6.5, 7, 7.5, 8, 8.5, 9, or 9.5% w / w. Any ranges of percentage w / w which may be formed from the combination of the aforementioned upper and lower endpoints are specifically contemplated. Thus, in some embodiments, Component (b) is present in the antimicrobial fraction of the composition of the invention in an amount of about 4.0% w / w, 4.5% w / w, about 5.0% w / w, about 5.5% w / w, about 6.0% w / w, about 6.5 % w / w, about 7.0% w / w, about 7.5 % w / w, about 8.0% w / w, about 8.5% w / w, about 9.0% w / w, about 9.5% w / w, or about 10.0% w / w. Preferably, Component (b) is present in the antimicrobial fraction of the composition in an amount of about 7.0% w / w, e.g. from about 6.0 % w / w to about 8.0% w / w, or about 6.5 % w / w to about 7.5% w / w. In other embodiments Component (b) is present in the in the antimicrobial fraction of the composition in an amount of about 7.04 %, e.g. from about 6.99% w / w to about 7.09% w / w. Citric acid is widely available from commercial suppliers, e.g. Jungbunzlauer. Other suppliers (or the supplier's approved distributors) are listed on the European Chemicals Agency (ECHA) Article 95 List of Approved substances and suppliers under the Biocidal Products Regulation. Water-soluble salts of lactic acid or citric acid are primarily alkali or alkali earth metal salts, of which the sodium, potassium, lithium, calcium, and magnesium salts are preferably used. Ammonium salts may also be used. The salt may be formed from any number of cations to the lactate or citrate anion. Preferably the watersoluble salts are non-hazardous / non-toxic to humans and higher organisms at the concentrations present in the compositions used in the methods of the invention. By “water soluble” it is meant that the salt can be dissolved to the required concentration in the aqueous antimicrobial composition of the invention. Conveniently, water soluble salts of lactic acid or citric acid are salts for which less than 1000 parts pure water are required to solubilise 1 part of the salt, e.g. less than 500, 250, 100, 50, 40, 30, 20, 10, 9, 8, 7, 6, 5, 4, 3, 2, or 1 parts pure water are required to solubilise 1 part of the salt. In embodiments in which a water-soluble salt of lactic or citric acid is used, the percentage weight of the component in the antimicrobial fraction of the composition of the invention is calculated on the basis or the lactate or citrate anion, i.e. not including the weight contribution of the cation. In accordance with the first aspect, Component (c) of the composition is an anionic polycarboxylate surfactant (a polymer of carboxylic acid monomers). In certain embodiments the anionic polycarboxylate surfactant is a homopolymer of one type of carboxylic acid or a heteropolymer of different types of carboxylic acids. The carboxylic acid monomers may carry a methyl, acetyl, sulphate, sulphonate, amino, deoxy, alcohol, aldehyde, ketone, or ester groups. In certain embodiments the anionic polycarboxylate surfactant acrylic acid comprises, acrylic acid, maleic acid, methacrylic acid. In certain embodiments the anionic polycarboxylate surfactant acrylic acid is a homopolymer of acrylic acid, a homopolymer of maleic acid, a homopolymer of methacrylic acid, a heteropolymer of acrylic acid, maleic acid and / or methacrylic acid, a copolymer of acrylic acid, maleic acid and / or methacrylic acid, or homo- / hetero- / co-polymers of amino acids (e.g. aspartate and glutamate) or a water-soluble salt thereof, e.g. a sodium salt thereof. In certain embodiments the anionic polycarboxylate surfactant does not contain an amino acid. In certain embodiments the anionic polycarboxylate surfactant is polyacrylic acid Polyacrylic acid is a polymer with the formula (CH2-CHCO2H)n The average molecular weight of the anionic polycarboxylate surfactant may be about 2000 to about 150000, e.g. about 5000 to about 12000 or about 7000 to about 10000. Any ranges of average Mw which may be formed from the combination of the aforementioned upper and lower endpoints are specifically contemplated. In other embodiments, the average molecular weight of the anionic polycarboxylate surfactant may be about 2000, about 5000, about 7000, about 10000, about 12000 or about 150000. The polycarboxylate surfactant is anionic insofar as the polycarboxylate adopts a negatively charged form when dissolved alone in distilled water. Water-soluble salts of polycarboxylates are primarily alkali or alkali earth metal salts, of which the sodium or potassium forms are preferably used. Ammonium salts may also be used. The salt may be formed from any number of cations to the polycarboxylate anion. Preferably the water-soluble salts selected are non-hazardous / non-toxic to humans and higher organisms at the concentrations present in the compositions used in the methods of the invention. The term “water soluble” may in the context of polycarboxylate salts may be construed in the same way as salts of citric acid or lactic acid. Preferably, the water-soluble salt of polyacrylic acid is sodium polyacrylate. Polyacrylic acid and sodium polyacrylate are widely available from commercial suppliers. For example, Flosperse™ 3000A (sodium polyacrylate), Flosperse™ 3000 (free acid) and Flosperse™ 3000N (ammonium polyacrylate) can be obtained from SNF / IMCD and can be used as Component (c) in the composition of the invention. Other manufacturers include Dow (Acumer™) available through Univar Solutions In other embodiments the anionic polycarboxylate surfactant is acrylic acid homopolymer (e.g. Flosperse™ 1000A, Flosperse™ 1000, Flosperse™ 1000N, Flosperse™ 3000A, Flosperse™ 3000, Flosperse™ 3000N, Flosperse™ 9000A, Flosperse™ 9000, Flosperse™ 9000N, Flosperse™ 10000A, Flosperse™ 10000, Flosperse™ 10000N, Flosperse™ 15000A, Flosperse™ 15000, Flosperse™ 15000N), maleic acid homopolymer (e.g. Flosperse™ PMA2A, Flosperse™ PMA3), maleic acid I acrylic acid copolymer (e.g. Flosperse™ 3030A CM, Flosperse™ 3030 CM, Flosperse™ 10030A CM, Flosperse™ 10030 CM), methacrylic acid homopolymer (e.g. Flosperse™ M 3000, Flosperse™ M 3000N, Flosperse™ 5000, Flosperse™ 9500, Flosperse™ 9500N) or acrylic acid / methacrylic acid copolymer (e.g. Flosperse™ 3031 CX). Without wishing to be bound by theory, the anionic polycarboxylate surfactant selected will be of a type and size which can combine with the other ingredients recited herein (i.e. carboxylic acid biocides and surfactants) to form micelles that are able to hold the active carboxylic acid ingredient within the micelles and release it to the environment over time thereby providing a long-lasting protection. More broadly, the anionic polycarboxylate surfactant selected will be of a type and size which can combine with the other ingredients recited herein (i.e. carboxylic acid biocides and surfactants) to provide an antimicrobial composition of sufficient residual efficacy when used in the amounts defined herein. Component (c) is present in the antimicrobial fraction of the composition of the invention in an amount from about 5 to about 15% w / w, e.g. about 6, 7, 8, 9, 10, 11, 12, 13, or 14% to about 15% w / w, or about 5% to about 6, 7, 8, 9, 10, 11, 12, 13, 14, or 15% w / w. Any ranges of percentage w / w which may be formed from the combination of the aforementioned upper and lower endpoints are specifically contemplated. Thus, in some embodiments, Component (c) is present in the antimicrobial fraction of the composition of the invention in an amount of about 5%, about 6%, about 7%, about 8% w / w, 9% w / w, 10% w / w, 11% w / w, 12% w / w, 13% w / w, 14% w / w, or about 15% w / w. Preferably, Component (c) is present in the composition in an amount of about 10% w / w, e.g. from about 8 % w / w to about 12% w / w, or about 9 % w / w to about 11 % w / w. In other embodiments Component (c) is present in the in the antimicrobial fraction of the composition in an amount of about 10.06 % w / w, e.g. from about 9.56% w / w to about 10.56% w / w, or about 10.01 % w / w to about 10.11 % w / w. In accordance with the first aspect, Component (d) is an a-Olefin (C12-C18) sulfonate, preferably an a-Olefin (C12-C18) sulfonate salt. Such compounds are classed as anionic surfactants. The a-Olefin of the a-Olefin sulfonate of use in the invention may be a C12, C13, C14, C15, Cie, or C17, to Cis, or a C12 to C13, C14, C15, C16, or Cis a-Olefin, e.g. a C12, C13, C14, C15, Cw, C17 or Cis a-Olefin. Any ranges of C chain length which may be formed from the combination of the aforementioned upper and lower endpoints for each C chain length are specifically contemplated. The aliphatic hydrocarbon chain may be saturated (alkane) or unsaturated (alkene). Mixtures of a-Olefin sulfonates recited above having a-Olefin parts of differing lengths and / or differing saturation levels is also expressly contemplated. In certain embodiments the a-Olefin sulfonate of use in the invention is an a-Olefin (C14-C16) sulfonate. The a-Olefin sulfonate compounds further contain a monovalent cation. Thus, in some embodiments the a-Olefin sulfonate of use in the invention contain a monovalent cation, such as sodium or potassium. Preferably, the monovalent cation is sodium. Ammonium salts may also be used. Thus, in preferred embodiments, Component (d) is sodium a-Olefin (C14-C16) sulfonate (CAS 68439-57-6). Sodium a-Olefin (C14-C16) sulfonate can be bought from Stepan, Surfachem, Azelis, Penta Italia Export SRL, Preparados Quimicos De Nevarra S.L. Sodium a-Olefin (C14-C16) sulfonate can be bought under the tradename BIO-TERGE® AS-40 HA-SB from these suppliers. Without wishing to be bound by theory, the a-Olefin sulfonate selected will be of a type and size which can combine with the other ingredients recited herein (i.e. carboxylic acid biocides and surfactants) to form micelles that are able to hold the active carboxylic acid ingredient within the micelles and release it to the environment over time thereby providing a long-lasting protection. More broadly, the a-Olefin sulfonate selected will be of a type and size which can combine with the other ingredients recited herein (i.e. carboxylic acid biocides and surfactants) to provide an antimicrobial composition of sufficient residual efficacy when used in the amounts defined herein. Component (d) is present in the antimicrobial fraction of the composition of the invention in an amount from about 9 to about 15% w / w, e.g. about 10, 11, 12, 13, or 14% to about 15% w / w, or about 9% to about 10, 11, 12,13, 14, or 15% w / w. Any ranges of percentage w / w which may be formed from the combination of the aforementioned upper and lower endpoints are specifically contemplated. Thus, in some embodiments, Component (d) is present in the antimicrobial fraction of the composition of the invention in an amount of about 9%, about 10%, about 11%, about 12%, about 13%, about 14% w / w, or about 15% w / w. Preferably, Component (d) is present in the antimicrobial fraction of the composition in an amount of about 11.5% w / w, e.g. from about 10.5 % w / w to about 12.5% w / w, or about 11.0 % w / w to about 12.0% w / w. In other embodiments Component (d) is present in the in the antimicrobial fraction of the composition in an amount of about 11.47 %, e.g. from about 10.47% w / w to about 12.47% w / w, or from about 11.42% w / w to about 11.52% w / w. In accordance with the first aspect, Component (e) of the composition is an anionic maleic acid copolymer surfactant, more specifically a maleic acid I non-carboxylic acid copolymer, preferably methyl vinyl ether-maleic acid copolymer having the below formula and the linear formula [CH2CH(OCH3)CH(CO2H)CH(CO2H)]n (CAS number 25153-40-6). The anionic maleic acid copolymer surfactant is anionic insofar as the maleic acid copolymer surfactant adopts a negatively charged form when dissolved alone in distilled water. In some embodiments the methyl vinyl ether-maleic acid copolymer of use in the invention has an average Mw of about 100,000 to about 4,000,000, e.g. about 150,000 to about 3,000,000, about 200,000 to about 2,000,000, about 300,000 to about 1,000,000, about 400,000 to about 900,000, about 500,000 to about 800,000 or about 600,000 to about 700,000. Any ranges of average Mw which may be formed from the combination of the aforementioned upper and lower endpoints are specifically contemplated. In other embodiments, the methyl vinyl ether-maleic acid copolymer of use in the invention has an average Mw of about 100,000, 150,000, 200,000, 300,000, 400,000, 500,000, 600,000, 700,000, 800,000, 900,000, 1,000,000, 2,000,000, 3,000,000, or 4,000,000. The anionic maleic acid copolymer surfactant may be provided as a water-soluble salt, primarily alkali or alkali earth metal salts (e.g. sodium, potassium, calcium, magnesium) or ammonium salts thereof. Without wishing to be bound by theory, the anionic maleic acid copolymer surfactant selected will be of a type and size which can provide sufficient residual efficacy to the carboxylic acid and non-(anionic maleic acid copolymer) agents when used in the amounts defined herein. More broadly, the anionic maleic acid copolymer surfactant selected will be of a type and size which can combine with the other ingredients recited herein (i.e. carboxylic acid biocides and surfactants) to form micelles that are able to hold the active carboxylic acid ingredient within the micelles and release it to the environment over time thereby providing a long-lasting protection. Maleic acid copolymers, and methyl vinyl ether-maleic acid copolymer specifically, can be obtained from a variety of suppliers. For example, methyl vinyl ether-maleic acid copolymer may be obtained from Ashland™ and is sold under the tradename Surfaguard™ MV-6. Component (e) is present in the antimicrobial fraction of the composition of the invention in an amount from about 6 to about 10% w / w, e.g. about 6.5, 7, 7.5, 8, 8.5, 9, or 9.5% to about 10% w / w, or about 6% to about 6.5, 7, 7.5, 8, 8.5, 9, or 9.5% w / w. Any ranges of percentage w / w which may be formed from the combination of the aforementioned upper and lower endpoints are specifically contemplated. Thus, in some embodiments, Component (e) is present in the antimicrobial fraction of the composition in an amount of about 6% w / w, 6.5% w / w, 7% w / w, 7.5% w / w, 8% w / w, 8.5% w / w, 9% w / w, 9.5% w / w, or about 10% w / w. Preferably, Component (e) is present in the antimicrobial fraction of the composition in an amount of about 7% w / w, e.g. from about 6% w / w to about 8% w / w, or about 6.5% w / w to about 7.5% w / w. In other embodiments Component (e) is present in the in the antimicrobial fraction of the composition in an amount of about 7.06%, e.g. from about 7.01 % w / w to about 7.11 % w / w. Without wishing to be bound by theory it is believed that the above described novel blend and relative proportions of carboxylic acid biocides and surfactants forms unique micelles that are able to hold the active ingredient within the micelles and release it to the environment over time thereby providing a long-lasting protection without the use of quaternary ammonium compounds. In certain specific embodiments there is provided an antimicrobial aqueous liquid composition consisting of (i) equal to or greater than 0.1 % w / w of an antimicrobial fraction consisting of components (a) to (e) (ii) equal to or less than 99.9% w / w water, and (iii) 0 to 5% w / w diluents, excipients or carriers other than water, wherein the sum of the percentage amounts of (i), (ii) and (ii) is 100%, and wherein the total weight of the antimicrobial fraction in the composition consists of (a) about 60 to about 70% w / w lactic acid or a water-soluble salt thereof (b) about 4 to about 10% w / w citric acid or a water-soluble salt thereof (c) about 5 to about 15% w / w polyacrylate (d) about 9 to about 15% w / w a-Olefin (C14-C16) sulfonate (e) about 6 to about 10% w / w methyl vinyl ether-maleic acid copolymer. In certain more specific embodiments there is provided an antimicrobial aqueous liquid composition consisting of (i) equal to or greater than 0.1 % w / w of an antimicrobial fraction consisting of components (a) to (e) (ii) equal to or less than 99.9% w / w water, and (iii) 0 to 5% w / w diluents, excipients or carriers other than water, wherein the sum of the percentage amounts of (i), (ii) and (ii) is 100%, and wherein the total weight of the antimicrobial fraction in the composition consists of (a) about 60 to about 70% w / w lactic acid or a water-soluble salt thereof (b) about 4 to about 10% w / w citric acid or a water-soluble salt thereof (c) about 5 to about 15% w / w sodium polyacrylate, e.g. in the form of Flosperse™ 3000A (d) about 9 to about 15% w / w sodium a-Olefin (C14-C16) sulfonate, e.g. in the form of BIO-TERGE® AS-40 HA-SB (e) about 6 to about 10% w / w methyl vinyl ether-maleic acid copolymer, e.g. in the form of Surfaguard™ MV-6. In accordance with the first aspect, the % w / w ratio (or weight ratio or mass ratio) of Components (a):(b):(c):(d):(e) is of about 7 :1:1:1:1 to about 13 : 1 : 2.5 : 2.5 : 2, about8: 1 : 1.2 : 1.2 : 1.2 to about 12 : 1 : 2.0 : 2.0:1.8, orabout9 : 1 : 1.3 : 1.3 : 1.3 to about 11 : 1 : 1.8 : 1.8 : 1.5. Any ratio ranges which may be formed from the combination of the respective upper and lower endpoints for each component are expressly contemplated herein. Preferably, the % w / w ratio of Components (a):(b):(c):(d):(e) in the antimicrobial fraction of the liquid composition of the invention is about 9.1 : 1 : 1.43 : 1.6 : 1, e.g. 8.9-9.3 : 1 : 1.2-1.6 : 1.4-1.8 : 0.8-1.2, or9.0-9.2 : 1 : 1.3-1.5 : 1.5-1.7 : 0.9-1.1 . In certain embodiments the antimicrobial fraction of the antimicrobial aqueous liquid composition amounts to about 40 to about 60% w / w of the composition, water amounts to about 40 to about 60% w / w of the composition, and diluents, excipients or carriers other than water amount to 0 to about 5% w / w of the composition. It will be recognised immediately that the sum of the above percentage amounts will be 100% in any composition provided in accordance with the invention. In these embodiments the antimicrobial fraction of the antimicrobial aqueous liquid composition may amount to about 40 to about 41, 42, 43, 44, 45, 46, 47, 48, 49, 50, 51, 52, 53, 54, 55, 56, 57, 58, 59 or 60% w / w, or about 40, 41, 42, 43, 44, 45, 46, 47, 48, 49, 50, 51, 52, 53, 54, 55, 56, 57, 58, or 59 to about 60% w / w of the composition. Any ranges of percentage w / w which may be formed from the combination of the aforementioned upper and lower endpoints are specifically contemplated. Thus, in some embodiments, the antimicrobial fraction of the antimicrobial aqueous liquid composition may amount to about 40, 41, 42, 43, 44, 45, 46, 47, 48, 49, 50, 51, 52, 53, 54, 55, 56, 57, 58, 59 or 60% w / w Preferably, the antimicrobial fraction of the antimicrobial aqueous liquid composition may amount to about 50% w / w, e.g. from about 48% w / w to about 52% w / w, or about 49% w / w to about 51 % w / w. In other embodiments the antimicrobial fraction of the antimicrobial aqueous liquid composition may amount to of about 49.71%, e.g. from about 49.51 % w / w to about 49.91 % w / w, e.g. about 49.61 % w / w to about 49.81% w / w. In these embodiments of the antimicrobial aqueous liquid composition, water may amount to about 40 to about 41, 42, 43, 44, 45, 46, 47, 48, 49, 50, 51, 52, 53, 54, 55, 56, 57, 58, 59 or 60% w / w, or about 40, 41, 42, 43, 44, 45, 46, 47, 48, 49, 50, 51, 52, 53, 54, 55, 56, 57, 58, or 59 to about 60% w / w of the composition. Any ranges of percentage w / w which may be formed from the combination of the aforementioned upper and lower endpoints are specifically contemplated. Thus, in some embodiments of the antimicrobial aqueous liquid composition, water may amount to about 40, 41,42, 43, 44, 45, 46, 47, 48, 49, 50, 51, 52, 53, 54, 55, 56, 57, 58, 59 or 60% w / w of the composition. Preferably, in the antimicrobial aqueous liquid composition, water may amount to about 50% w / w, e.g. from about 48% w / w to about 52% w / w, or about 49% w / w to about 51 % w / w of the composition. In other embodiments of the antimicrobial aqueous liquid composition water may amount to of about 50.29%, e.g. from about 49.79% w / w to about 50.79% w / w, e.g. about 50.19% w / w to about 50.39% w / w of the composition. In these embodiments of the antimicrobial aqueous liquid composition, diluents, excipients or carriers other than water may amount to about 0.01 % w / w to about 0.05%, 0.1%, 0.5%, 1%, 1.5%, 2.0%, 2,5%, 3.0%, 3.5%, 4.0%, 4.5%, or 5.0%, or about 0.01%, 0.05%, 0.1%, 0.5%, 1%, 1.5%, 2.0%, 2,5%, 3.0%, 3.5%, 4.0%, 4.5% w / w to about 5.0% w / w of the composition. Any ranges of percentage w / w which may be formed from the combination of the aforementioned upper and lower endpoints are specifically contemplated. Thus, in some embodiments of the antimicrobial aqueous liquid composition, diluents, excipients or carriers other than water may amount to about 0.01 %, 0.05%, 0.1%, 0.5%, 1%, 1.5%, 2.0%, 2,5%, 3.0%, 3.5%, 4.0%, 4.5% w / w or 5.0% w / w of the composition. In other embodiments the antimicrobial fraction of the antimicrobial aqueous liquid composition amounts to about 1 to about 5% w / w of the composition, water amounts to about 95 to about 99% w / w of the compositions and diluents, excipients or carriers other than water amount to 0% to about 0.5% w / w of the composition. It will be recognised immediately that the sum of the above percentage amounts will be 100% in any composition provided in accordance with the invention. In these embodiments the antimicrobial fraction of the antimicrobial aqueous liquid composition may amount to about 1.0 to about 1.5, 2.0, 2.5, 3.0, 3.5, 4.0, 4.5 or 5.0% w / w, or about 1.0, 1.5, 2.0, 2.5, 3.0, 3.5, 4.0, or 4.5% w / w to about 5.0% w / w of the composition. Any ranges of percentage w / w which may be formed from the combination of the aforementioned upper and lower endpoints are specifically contemplated. Thus, in some embodiments, the antimicrobial fraction of the antimicrobial aqueous liquid composition may amount to about 1.0, 1.5, 2.0, 2.5, 3.0, 3.5, 4.0, 4.5 or 5.0% w / w. Preferably, the antimicrobial fraction of the antimicrobial aqueous liquid composition may amount to about 2.5% w / w, e.g. from about 2.0% w / w to about 3.0% w / w, or about 2.2% w / w to about 2.8% w / w. In other embodiments the antimicrobial fraction of the antimicrobial aqueous liquid composition may amount to of about 2.49%, e.g. from about 2.44% w / w to about 2.54% w / w, e.g. about 2.47% w / w to about 2.51% w / w. In these embodiments of the antimicrobial aqueous liquid composition, water may amount to about 95.0 to about 95.5, 96.0, 96.5, 97.0, 97.5, 98.0, 98.5, or about 95.0, 95.5, 96.0, 96.5, 97.0, 97.5, 98.0, 98.5 to about 99.0% of the composition. Any ranges of percentage w / w which may be formed from the combination of the aforementioned upper and lower endpoints are specifically contemplated. Thus, in some embodiments of the antimicrobial aqueous liquid composition, water may amount to about 95.0, 95.5, 96.0, 96.5, 97.0, 97.5, 98.0, 98.5 or 99.0% w / w of the composition. Preferably, in the antimicrobial aqueous liquid composition, water may amount to about 97.5% w / w, e.g. from about 96.5% w / w to about 98.5% w / w, or about 97% w / w to about 98% w / w of the composition. In other embodiments of the antimicrobial aqueous liquid composition water may amount to of about 97.51%, e.g. from about 97.01% w / w to about 98.01% w / w, e.g. about 97.41% w / w to about 97.61% w / w of the composition. In these embodiments of the antimicrobial aqueous liquid composition, diluents, excipients or carriers other than water may amount to about 0.001 % w / w to about 0.005%, 0.01%, 0.05%, 0.1%, 0.15%, 0.20%, 0.25%, 0.30%, 0.35%, 0.40%, 0.45%, or 05%, or about 0.001%, 0.005%, 0.01%, 0.05%, 0.1%, 0.15%, 0.20%, 0.25%, 0.30%, 0.35%, 0.40%, or 0.45% w / w to about 0.5% w / w of the composition. Any ranges of percentage w / w which may be formed from the combination of the aforementioned upper and lower endpoints are specifically contemplated. Thus, in some embodiments of the antimicrobial aqueous liquid composition, diluents, excipients or carriers other than water may amount to about 0.001%, 0.005%, 0.01%, 0.05%, 0.1%, 0.15%, 0.20%, 0.25%, 0.30%, 0.35%, 0.40%, 0.45%, or 0.05% w / w of the composition. In addition to components (a)-(e) of the antimicrobial fraction and water, the aqueous antimicrobial composition of the invention may comprise suitable carriers, excipients, and diluents, e.g. to enhance storage life, sprayability, to meet safety requirements (e.g. dyes and bittering agents), to improve flavour, sweetness and smell or to control the physical properties of the formulation. Examples of suitable compounds are glucose, sucrose, maltose, galactose, fructose, lactose, dextrose, sucrose, sorbitol, mannitol, starches, gum acacia, calcium phosphate, inert alginates, tragacanth, gelatine, calcium silicate, microcrystalline cellulose, polyvinylpyrrolidone, cellulose, glycol, polyethylene, propylene glycol, methyl cellulose, methylhydroxybenzoates, propyl hydroxybenzoates, talc, magnesium stearate, pH buffers, alkalis and inorganic acids. For completeness it should be made clear that these excipients, carriers or other diluents are not any of Components (a)-(e), or water. As the above-recited components are non-hazardous / non-toxic to humans and other higher organisms (mammals, birds, fish, reptiles, insects and plants) at the concentrations present in the compositions used in the methods of the invention and do not accumulate in the environment following such methods, any further components are preferably also non-hazardous / non-toxic to humans and other higher organisms at the concentrations present in the compositions used in the methods of the invention and are essentially biodegradable. Where the sources of Components (a)-(e) and / or the water source contain trace amounts of impurities, e.g. minerals, residual by-products of the manufacturing process or the like, these maybe consider to be part of the diluent, carrier and excipient fraction. In the context of the present invention “biodegradable” means that the components of the compositions of the invention and thus the compositions themselves degrade in the environment given sufficient time, e.g. a month, 6 months, a year, 2 years or 5 years. Similarly, a compound or composition does not accumulate in the environment if amounts thereof are undetectable, or at least are below activity thresholds, a month, 6 months, a year, 2 years or 5 years following initiation of daily, weekly, or monthly use. In the context of the invention “non-hazardous (or “non-toxic”) to humans and other higher organisms” means that a substance, at the concentrations present in the compositions used in the methods of the invention, or in amounts that may typically accumulate immediately following such use, is not acutely or chronically harmful to the health or well-being of humans and other higher organisms . Such substances may be selected from those substances Generally Regarded as Safe under sections 201 (s) and 409 of the Federal Food, Drug, and Cosmetic Act and / or those listed as safe under relevant local biocide ordinance (e.g. the EU Biocide Regulation No 528 / 2012). The carriers, excipients, and diluents which may be included are typically inert, at least in the context of the combat of microorganisms as described herein. Thus, in preferred embodiments the antimicrobial aqueous liquid composition of the invention does not comprise further antimicrobial compounds or any further active agents In particular, the antimicrobial liquid compositions of the invention will be essentially or entirely free of quaternary ammonium compounds (QACs). This term includes quaternary ammonium cations (positively-charged polyatomic ions of the structure [NR4]+, also referred to as quats), quaternary ammonium salts, and polyquats . In other embodiments the aqueous compositions of the invention do not comprise a bactericidal alcohol. Bactericidally active alcohols include aliphatic alcohols and phenyl-aliphatic alcohols, i.e. aliphatic alcohols substituted by phenyl groups in the aliphatic C-chain, which may contain one or more hydroxyl groups. Of the aliphatic alcohols, straight-chain or branched, unsubstituted or mono- or disubstituted aliphatic alcohols containing from 1 to 6 carbon atoms in the alkyl or alkylene radical are mentioned specifically. Within the above-mentioned group, straightchain or branched unsubstituted aliphatic alcohols containing from 2 to 4 carbon atoms in the alkyl or alkylene radical are mentioned specifically. Alcohols such as these are ethanol, n-propanol or isopropanol. The mono- or disubstituted aliphatic alcohols mentioned above may be straight-chain or branched, aliphatic C2-C4 alcohols substituted by 1 or 2 substituents from the group Cl, Br or NO2. Of these compounds, 2-bromo-2-nitro-1,3-propane diol is mentioned specifically. Straightchain or branched, unsubstituted or mono- or disubstituted phenyl-aliphatic alcohols containing from 1 to 3 carbon atoms in the alkylene radical instead of straight aliphatic alcohols are mentioned specifically. "Phenyl-aliphatic" alcohols are understood to be alcohols in which the alcohol function is attached to the alkyl chain and the alkyl radical additionally contains a phenyl radical as substituent. Within the group of alcohols such as these, straight-chain, unsubstituted phenylaliphatic alcohols containing 1 to 3 carbon atoms in the alkylene radical or straight-chain phenyl-aliphatic alcohols containing from 1 to 3 carbon atoms in the alkylene radical substituted by 1 or 2 substituents from the group comprising Cl, Br or NO2, e.g. benzyl-alcohol, are mentioned specifically. The antimicrobial compositions of the invention are aqueous liquid compositions. An “aqueous liquid composition” is a composition in which the solvent portion is comprised substantially, e.g. predominantly or essentially of water, e.g. at least 80%, 90%, 95%, 99% or 100% of the solvent portion of the entity is water. Thus, in certain embodiments the antimicrobial composition of the invention does not contain a non-polar, e.g. organic, solvent, or if it does, the amount of non-polar solvent is less, e.g. significantly less, than the amount of water in the composition. Expressed numerically the amount of non-polar solvent in the composition is preferably less than 50%, 30%, 20%, 10%, 5%, or 1% w / w of the amount of water solvent in the composition. Solvents with a dielectric constant of less than 15, e.g. less than 12, 10, 8 or 5, are generally considered to be non-polar. The aqueous antimicrobial compositions of the invention are liquid insofar as their state of matter is assessed at the temperatures at which they are used, e.g. are liquid at temperatures above 0°C when under 1 atm pressure. Carriers that influence the viscosity and / or rheology of the composition are also of particular note as further components of the compositions of the invention. More specifically the inclusion of polymer carriers in the composition may allow for the composition to be provided in a form other than a simple liquid, e.g. as a viscous liquid, a semi solid or a solid, e.g. as a hydrogel or hydrocolloid gel. Such forms may be advantageous in the sanitisation of body surfaces, e.g. skin, scalp, hair, teeth, gums and other oral, buccal or dental surfaces. In this context toothpastes, dental gels, dental foams, oral sprays and mouthwashes are mentioned specifically. Gel-forming (e.g. hydrogel or hydrocolloid gel forming) polymeric substances, include, but are not limited to, alginate, cellulose (e.g. oxidised regenerated cellulose, methylcellulose, carboxymethylcellulose, hydroxyethylcellulose), collagen, pectin, elastin, fibronectin. Where the use to which the antimicrobial composition is put is in the in vitro treatment of inanimate surfaces and locations the composition may be considered a sanitising, disinfecting, antiseptic or sterilising formulation. Where the use to which the antimicrobial composition is put is in the combat of microbial contamination on an animate surface, i.e. a surface of and on or in a living human or animal body (in vivo), or an inanimate surface on or in a living human or animal body, in other words as a pharmaceutical, the aqueous composition is provided as a pharmaceutically acceptable composition or formulation for application to the surface to be treated. Such formulations can also be used in ex vivo treatments of tissues and body parts. The skilled person would be familiar with suitable pharmaceutically acceptable carriers, excipients and diluents and would understand which of those recited above are in such categories. Thus, in a further embodiment the antimicrobial aqueous liquid composition of the invention is provided as an antimicrobial aqueous pharmaceutical composition, i.e. comprising the recited components and, if present, pharmaceutically acceptable carriers, diluents or excipients. In certain embodiments the antimicrobial aqueous liquid composition of the invention does not contain any diluents, excipients or carriers other than water. In other words, the antimicrobial aqueous liquid composition of the invention consists of parts (i) and (ii) only. In further preferred embodiments the antimicrobial liquid composition consists essentially of components (a) to (e) and water, i.e. any excipients, carriers or other active agents are present in negligible amounts. This may be expressed as an antimicrobial composition consisting of: (a) about 27 to about 37% w / w lactic acid or a water-soluble salt thereof (b) about 0.5 to about 6.5% w / w citric acid or a water-soluble salt thereof (c) about 1 to about 10% w / w anionic polycarboxylate surfactant (d) about 3 to about 8% w / w a-Olefin (Cn-Cis) sulfonate (e) about 2.5 to about 6.5% w / w anionic maleic acid co-polymer surfactant; and (f) about 32% to about 66% w / w water, wherein the sum of the percentage amounts of (a)-(f) is 100%. Component (a) is present in these embodiments of the composition of the invention in an amount from about 27 to about 37% w / w, e.g. about 28%, 29%, 30%, 31%, 32%, 33%, 34%, 35%, or 36% to about 37%, or about 27% to about 28%, 29%, 30%, 31%, 32%, 33%, 34%, 35%, or 36% w / w. Any ranges of percentage w / w which may be formed from the combination of the aforementioned upper and lower endpoints are specifically contemplated. Thus, Component (a) may be present in the composition in an amount of about 27%, 28%, 29%, 30%, 31%, 32%, 33%, 34%, 35%, 36%, or about 37% w / w. Preferably, Component (a) is present in the composition in an amount of about 32% w / w, e.g. from about 30% w / w to about 34% w / w, or about 31 % w / w to about 33% w / w. In other embodiments Component (a) is present in the composition in an amount of about 31.5% w / w to about 32.5% w / w, or about 31.8% w / w to about 32.2% w / w. Component (b) is present in these embodiments of the composition of the invention in an amount from about 0.5 to about 6.5% w / w, e.g. about 1.0, 1.5, 2.0, 2.5, 3.0, 3.5, 4.0, 4.5, 5.0, 5.5%, or 6.0% to about 6.5% w / w, or about 0.5% to about 1.0, 1.5, 2.0, 2.5, 3.0, 3.5, 4.0, 4.5, 5.0, 5.5, 6.0%, or 6.5% w / w. Any ranges of percentage w / w which may be formed from the combination of the aforementioned upper and lower endpoints are specifically contemplated. Thus, in some embodiments, Component (b) is present in composition of the invention in an amount of about 0.5, 1.0, 1.5, 2.0, 2.5, 3.0, 3.5, 4.0, 4.5, 5.0, 5.5, 6.0% or about 6.5% w / w. Preferably, Component (b) is present in the composition in an amount of about 3.5% w / w, e.g. from about 2.5 % w / w to about 4.5% w / w, or about 3.0 % w / w to about 4.0% w / w. In other embodiments Component (b) is present in the in the antimicrobial fraction of the composition in an amount of from about 3.2% w / w to about 3.7, or about 3.4% w / w to about 3.6% w / w. Component (c) is present in these embodiments of the composition of the invention in an amount from about 1 to about 10% w / w, e.g. about 2, 3, 4, 5, 6, 7, 8, or 9% to about 10% w / w, or about 1% to about 2, 3, 4, 5, 6, 7, 8, or 9% w / w. Any ranges of percentage w / w which may be formed from the combination of the aforementioned upper and lower endpoints are specifically contemplated. Thus, in some embodiments, Component (c) is present in the composition of the invention in an amount of about 1%, about 2%, about 3%, about 4%, about 5%, about 6%, about 7%, about 8% w / w, about 9% w / w, or about 10% w / w. Preferably, Component (c) is present in the composition in an amount of about 5% w / w, e.g. from about 3 % w / w to about 7% w / w, or about 4 % w / w to about 6% w / w. In other embodiments Component (c) is present in the in the antimicrobial fraction of the composition in an amount of about 4.5% w / w to about 5.5% w / w, or about 4.9% w / w to about 5.1 % w / w. Component (d) is present in these embodiments of the composition of the invention in an amount from about 3% to about 8% w / w, e.g. about 3.5%, 4.0%, 4.5%, 5.0%, 5.5%, 6.0%, 6.5%, 7.0%, or 7.5% to about 8.0%, or about 3.0% to about 3.5%, 4.0%, 4.5%, 5.0%, 5.5%, 6.0%, 6.5%, 7.0%, 7.5% or 8.0%,w / w. Any ranges of percentage w / w which may be formed from the combination of the aforementioned upper and lower endpoints are specifically contemplated. Thus, in some embodiments, Component (d) is present in the composition of the invention in an amount of about 3.0%, 3.5%, 4.0%, 4.5%, 5.0%, 5.5%, 6.0%, 6.5%, 7.0%, 7.5% or 8.0% w / w. Preferably, Component (d) is present in the composition in an amount of about 5.7% w / w, e.g. from about 5.2 % w / w to about 6.2% w / w, or about 5.6 % w / w to about 5.8% w / w. In other embodiments Component (d) is present in the in the antimicrobial fraction of the composition in an amount from about 5.65% w / w to about 5.75% w / w, or from about 5.69% w / w to about 5.71% w / w. Component (e) is present in these embodiments of the composition of the invention in an amount from about 2.5% to about 6.5% w / w, e.g. about 3.0, 3.5, 4.0, 4.5, 5.0, 5.5 or 6.0% to about 6.5% w / w, or about 2.5% to about 3.0, 3.5, 4.0, 4.5, 5.0, 5.5, or 6.0% w / w. Any ranges of percentage w / w which may be formed from the combination of the aforementioned upper and lower endpoints are specifically contemplated. Thus, in some embodiments, Component (e) is present in the composition in an amount of about 3.0, 3.5, 4.0, 4.5, 5.0, 5.5, 6.0% or about 6.5% w / w Preferably, Component (e) is present in the composition in an amount of about 3.5% w / w, e.g. from about 2.5 % w / w to about 4.5% w / w, or about 3.0 % w / w to about 4.0% w / w. In other embodiments Component (e) is present in the in the antimicrobial fraction of the composition in an amount of about 3.51 %, e.g. from about 3.21% w / w to about 3.71, or about 3.41% w / w to about 3.61% w / w. Component (f) is present in these embodiments of the composition of the invention in an amount from about 32 to about 66% w / w, e.g. about 34%, 36%, 38%, 40%, 42%, 44%, 46%, 48%, 50%, 52%, 54%, 56%, 58%, 60%, 62%, or 64% to about 66%, or about 32% to about 34%, 36%, 38%, 40%, 42%, 44%, 46%, 48%, 50%, 52%, 54%, 56%, 58%, 60%, 62%, or 64% w / w. Any ranges of percentage w / w which may be formed from the combination of the aforementioned upper and lower endpoints are specifically contemplated. Thus, Component (f) may be present in the composition in an amount of about 32%, 34%, 36%, 38%, 40%, 42%, 44%, 46%, 48%, 50%, 52%, 54%, 56%, 58%, 60%, 62%, 64% or about 66% w / w. Preferably, Component (f) is present in the composition in an amount of about 50% w / w, e.g. from about 48% w / w to about 52% w / w, or about 49% w / w to about 51% w / w. In other embodiments Component (f) is present in the in the composition in an amount of about 50.29% w / w, e.g. from about 49.79 to about 50.79% w / w, or about 50.19% w / w to about 50.39% w / w. The selected percentage w / w of each component will be such that the liquid composition so formed will be antimicrobial and have residual efficacy as defined herein. Any combination of the examples of components (a)-(e) disclosed herein to may be applied to this embodiment. In one specific embodiment the invention provides an antimicrobial composition consisting of: (a) 32% w / w lactic acid or a water-soluble salt thereof (b) 3.5% w / w citric acid or a water-soluble salt thereof (c) 5.0% w / w anionic polycarboxylate surfactant (d) 5.7% w / w a-Olefin (C12-C18) sulfonate (e) 3.51% w / w anionic maleic acid co-polymer surfactant; and (f) 50.29% w / w water. In a more specific embodiment the invention provides an antimicrobial composition consisting of: (a) 32% w / w lactic acid or a water-soluble salt thereof (b) 3.5% w / w citric acid or a water-soluble salt thereof (c) 5.0% w / w sodium polyacrylate (d) 5.7% w / w sodium a-Olefin (Cu-Cw) sulfonate (e) 3.51% w / w methyl vinyl ether-maleic acid copolymer; and (f) 50.29% w / w water. In a still more specific embodiment the invention provides an antimicrobial composition consisting of: (a) 32% w / w lactic acid or a water-soluble salt thereof (b) 3.5% w / w citric acid or a water-soluble salt thereof (c) 5.0% w / w sodium polyacrylate in the form of Flosperse™ 3000A (d) 5.7% w / w sodium a-Olefin (Cu-Cw) sulfonate in the form of BIOTERGE® AS-40 HA-SB (e) 3.51% w / w methyl vinyl ether-maleic acid copolymer in the form of Surfaguard™ MV-6; and (f) 50.29% w / w water. The above-described aspects and embodiments can be considered to relate to a concentrated form of the antimicrobial liquid composition of the invention. In a further aspect the invention provides a dry solid composition consisting of (a) about 60 to about 70% w / w lactic acid or a water-soluble salt thereof (b) about 4 to about 10% w / w citric acid or a water-soluble salt thereof (c) about 5 to about 15% w / w anionic polycarboxylate surfactant (d) about 9 to about 15% w / w a-Olefin (C12-C18) sulfonate (e) about 6 to about 10% w / w anionic maleic acid co-polymer surfactant, and (f) 0 to 5% w / w diluents, excipients or carriers It will be recognised immediately that the sum of the percentage amounts of (a)-(f) will be 100% in any composition provided in accordance with the invention. The above discussion of the features of the antimicrobial aqueous liquid compositions of use in the antimicrobial methods of the invention applies mutatis mutandis as appropriate to this aspect. In particular the dry solid composition may consist of any combination of the examples of components (a)-(e) and diluents, excipients or carriers disclosed herein. By “dry” it is meant that the solid composition is substantially, e.g. essentially, water-free (moisture-free). This may be expressed as a water content of less than 5% w / w, e.g. less than 4.5%, 4%, 3.5%, 3%, 2.5%, 2%, 1.5% or 1% w / w as measured by weight loss on drying or chemically by the Karl Fischer method (United States Pharmacopeia; European Pharmacopoeia). The solid composition of the invention is preferably dried by freeze drying (lyophilisation). The precise form of the solid composition of the invention is not limited. It may be single entity or in finely divided, e.g. particulate or powder, form. In certain embodiments the powder / particulate form may be provided compressed into a tablet or encapsulated. The solid may be a dry gel or sponge or a film or sheet. Thus, in some embodiments, the antimicrobial liquid composition of the invention described so far may be diluted with a suitable amount of aqueous (preferably water) diluent to form ready to use compositions. In certain embodiments, the antimicrobial liquid compositions of the invention may be diluted about 100x, 90x, 80x, 70x, 60x, 50x, 45x, 40x, 35x, 30x, 25x, 20x, 19x, 18x, 17x, 16x, 15x, 14x, 13x, 12x, 11x, 10x, or about 5x prior to use, e.g. in the methods of the invention described below. Any ranges of dilution factor which may be formed from the combination of the aforementioned values are specifically contemplated. Preferably, the antimicrobial liquid composition of the invention is diluted by a factor of about 40x to about 5x, e.g. about 35x to about 10x, about 30x to about 15x, most preferably about 20x. Expressed differently, the antimicrobial liquid composition of the invention may be diluted to a concentration which is about 10%, 9%, 8%, 7%, 6%, 5%, 4%, 3%, 2%, or about 1% of its original concentration or less. Any ranges of dilution factor which may be formed from the combination of the aforementioned values are specifically contemplated. Preferably, the antimicrobial liquid composition of the invention is diluted to a concentration which is about 5% of its original concentration, e.g. to a concentration which is about 1 to 10%, 2 to 9%, 3 to 7%, or 4 to 6% of its original concentration. Any appropriate aqueous diluent may be used to achieve the required dilution of the antimicrobial liquid compositions described herein. In preferred embodiments, the aqueous diluent is water, or an aqueous solution or suspension carrying the above described carriers, excipients or diluents in amounts permitted by the parameters of the invention disclosed herein. In particular the diluent may comprise organic or inorganic salts, pH buffers, acids and / or alkalis. Most conveniently, the diluent is water, in particular purified water. Thus, the invention also provides dilute (i.e. “ready to use”) antimicrobial liquid compositions. Specific examples of dilute antimicrobial aqueous liquid compositions of the invention include the following. An antimicrobial composition consisting of: (a) about 1.35 to about 1.75% w / w lactic acid or a water-soluble salt thereof (b) about 0.025 to about 0.325% w / w citric acid or a water-soluble salt thereof (c) about 0.05 to about 0.5% w / w anionic polycarboxylate surfactant (d) about 0.15 to about 0.4% w / w a-Olefin (C12-C18) sulfonate (e) about 0.125 to about 0.325% w / w anionic maleic acid co-polymer surfactant; and (f) about 96.7 to about 98.3% w / w water, wherein the sum of the percentage amounts of (a)-(f) is 100%. Component (a) is present in these embodiments of the composition of the invention in an amount from about 1.35 to about 1.70% w / w, e.g. about 1.40%, 1.45%, 1.50%, 1.55%, 1.60%, 1.65%, or 1.70% to about 1.75%, or about 1.35% to about 1.40%, 1.45%, 1.50%, 1.55%, 1.60%, 1.65%, 1.70% or 1.75% w / w. Any ranges of percentage w / w which may be formed from the combination of the aforementioned upper and lower endpoints are specifically contemplated. Thus, Component (a) may be present in the composition in an amount of about 1.35%, 1.40%, 1.45%, 1.50%, 1.55%, 1.60%, 1.65%, 1.70% or about 1.75% Preferably, Component (a) is present in the composition in an amount of about 1.6% w / w, e.g. from about 1.5% w / w to about 1.7% w / w, or about 1.55 % w / w to about 1.65% w / w. In other embodiments Component (a) is present in the composition in an amount of about 1.58% w / w to about 1.62% w / w, or about 1.59% w / w to about 1.61% w / w. Component (b) is present in these embodiments of the composition of the invention in an amount from about 0.025 to about 0.325% w / w, e.g. about 0.05, 0.075, 0.1, 0.125, 0.15, 0.175, 0.2, 0.225, 0.25, 0.275, or 0.3% to about 0.325%, or about 0.025% to about 0.05, 0.075, 0.1, 0.125, 0.15, 0.175, 0.2, 0.225, 0.25, 0.275, or about 0.3% w / w. Any ranges of percentage w / w which may be formed from the combination of the aforementioned upper and lower endpoints are specifically contemplated. Thus, in some embodiments, Component (b) is present in composition of the invention in an amount of about 0.025, 0.05, 0.075, 0.1, 0.125, 0.15, 0.175, 0.2, 0.225, 0.25, 0.275, 0.3 or about 0.325%. Preferably, Component (b) is present in the composition in an amount of about 0.175% w / w, e.g. from about 0.165 % w / w to about 0.185% w / w, or about 0.170 % w / w to about 0.180% w / w. Component (c) is present in these embodiments of the composition of the invention in an amount from about 0.05 to about 0.5% w / w, e.g. about 0.10, 0.15, 0.20, 0.25, 0.30, 0.35, 0.40, or 0.45 to about 0.5% w / w, or about 0.05% to about 0.10, 0.15, 0.20, 0.25, 0.30, 0.35, 0.40, or about 0.45% w / w. Any ranges of percentage w / w which may be formed from the combination of the aforementioned upper and lower endpoints are specifically contemplated. Thus, in some embodiments, Component (c) is present in the composition of the invention in an amount of about 0.05, 0.10, 0.15, 0.20, 0.25, 0.30, 0.35, 0.40, 0.45 or about 0.5% % w / w. Preferably, Component (c) is present in the composition in an amount of about 0.25% w / w, e.g. from about 0.15 % w / w to about 0.35% w / w, or about 0.2 % w / w to about 0.3% w / w. In other embodiments Component (c) is present in the composition in an amount of about 0.22% w / w to about 0.28% w / w, or about 0.24% w / w to about 0.26% w / w. Component (d) is present in these embodiments of the composition of the invention in an amount from about 0.15 to about 0.4% w / w, e.g. about 0.175, 0.2, 0.225, 0.25, 0.275, 0.3, 0.325, 0.35, or 0.375% to about 0.4%, or about 0.15% to about 0.175, 0.2, 0.225, 0.25, 0.275, 0.3, 0.325, 0.35, or 0.375% w / w. Any ranges of percentage w / w which may be formed from the combination of the aforementioned upper and lower endpoints are specifically contemplated. Thus, in some embodiments, Component (d) is present in the composition of the invention in an amount of about 0.15, 0.175, 0.2, 0.225, 0.25, 0.275, 0.3, 0.325, 0.35, 0.375% or about 0.4% w / w. Preferably, Component (d) is present in the composition in an amount of about 0.285% w / w, e.g. from about 0.185 % w / w to about 0.385% w / w, or about 0.235 % w / w to about 0.335% w / w. In other embodiments Component (d) is present in the composition in an amount from about 0.28 % w / w to about 0.29% w / w, or from about 0.283% w / w to about 0.287% w / w. Component (e) is present in these embodiments of the composition of the invention in an amount from about 0.125 to about 0.325% w / w, e.g. about 0.15, 0.175, 0.2, 0.225, 0.25, 0.275, or 0.3% to about 0.325%, or about 0.125% to about 0.15, 0.175, 0.2, 0.225, 0.25, 0.275, or about 0.3% w / w. Any ranges of percentage w / w which may be formed from the combination of the aforementioned upper and lower endpoints are specifically contemplated. Thus, in some embodiments, Component (e) is present in the composition of the invention in an amount of about 0.125, 0.15, 0.175, 0.2, 0.225, 0.25, 0.275, 0.3 or about 0.325%. Preferably, Component (e) is present in the composition in an amount of about 0.176% w / w, e.g. from about 0.166 % w / w to about 0.186% w / w, or about 0.171 % w / w to about 0.181% w / w or about 0.174% w / w to about 0.178% w / w. Component (f) is present in these embodiments of the composition of the invention in an amount from about 96.7 to about 98.3% w / w, e.g. about 96.8, 96.9, 97.0, 97.1, 97.2, 97.3, 97.4, 97.5, 97.6, 97.8, 97.9, 98.1, or 98.2 to about 98.3% w / w, or about 96.7 to about 96.8, 96.9, 97.0, 97.1, 97.2, 97.3, 97.4, 97.5, 97.6, 97.8, 97.9, 98.1, or 98.2% w / w. Any ranges of percentage w / w which may be formed from the combination of the aforementioned upper and lower endpoints are specifically contemplated. Thus, Component (f) may be present in the composition in an amount of about 96.7, 96.8, 96.9, 97.0, 97.1, 97.2, 97.3, 97.4, 97.5, 97.6, 97.8, 97.9, 98.1, 98.2 or 98.3 w / w. Preferably, Component (f) is present in the composition in an amount of about 97.5% w / w, e.g. from about 97.0% w / w to about 98.0% w / w, or about 97.2% w / w to about 97.7% w / w. In other embodiments Component (f) is present in the in the composition in an amount of about 97.514% w / w, e.g. from about 97.49 to about 97.53% w / w, or about 97.50% w / w to about 97.52% w / w. The selected percentage w / w of each component will be such that the liquid composition so formed will be antimicrobial and have residual efficacy as defined herein. Any combination of the examples of components (a)-(e) disclosed herein to may be applied to this embodiment. In one specific embodiment the invention provides an antimicrobial composition consisting of: (a) 1.6% w / w lactic acid or a water-soluble salt thereof (b) 0.175% w / w citric acid or a water-soluble salt thereof (c) 0.25% w / w anionic polycarboxylate surfactant (d) 0.285% w / w a-Olefin (Cn-Cis) sulfonate (e) 0.176% w / w anionic maleic acid co-polymer surfactant; and (f) 97.514% w / w water. In a more specific embodiment the invention provides an antimicrobial composition consisting of: (a) 1.6% w / w lactic acid or a water-soluble salt thereof (b) 0.175% w / w citric acid or a water-soluble salt thereof (c) 0.25% w / w sodium polyacrylate (d) 0.285% w / w sodium a-Olefin (Cu-Cw) sulfonate (e) 0.176% w / w methyl vinyl ether-maleic acid copolymer; and (f) 97.514% w / w water. In a still more specific embodiment the invention provides an antimicrobial composition consisting of: (a) 1.6% w / w lactic acid or a water-soluble salt thereof (b) 0.175% w / w citric acid or a water-soluble salt thereof (c) 0.25% w / w sodium polyacrylate in the form of Flosperse™ 3000A (d) 0.285% w / w a-Olefin (Cu-Cw) sulfonate in the form of BIOTERGE® AS-40 HA-SB (e) 0.176% w / w methyl vinyl ether-maleic acid copolymer in the form of Surfaguard™ MV-6; and (f) 97.514% w / w water. In a further aspect the invention provides a kit comprising, optionally in separate containers: (i) lactic acid or a water-soluble salt thereof, optionally in an aqueous solution; (ii) citric acid or a water-soluble salt thereof, optionally in an aqueous solution; (iii) at least one anionic polycarboxylate surfactant, optionally in an aqueous solution, (iv) at least one a-Olefin (C12-C18) sulfonate, optionally in an aqueous solution, (v) at least one anionic maleic acid co-polymer surfactant, optionally in an aqueous solution and (vi) instructions to prepare an antimicrobial aqueous liquid composition as defined herein, and optionally (vii) further components, e.g. excipients, carriers or other active agents, e.g. as defined herein. The instructions of component (vi) may for example comprise instructions to combine components (i) to (v) (and (vii) if present) in sufficient amounts to prepare said antimicrobial aqueous liquid composition or to combine components (i) to (v) (and (vii) if present) with an aqueous diluent in sufficient amounts to prepare said antimicrobial liquid aqueous composition. The above discussion of the features of the antimicrobial aqueous liquid compositions of use in the antimicrobial methods of the invention applies mutatis mutandis as appropriate to this aspect. In a further aspect the invention provides a kit comprising: (i) a concentrated form of a ready to use antimicrobial aqueous liquid composition described herein, or (ii) a dry solid composition as described herein, and (iii) instructions to prepare the ready to use form of the antimicrobial aqueous liquid composition as described herein, e.g. by a method recited below. In another aspect, the invention provides a woven or non-woven fabric or sponge carrying, preferably impregnated with, a dilute form of the composition of the invention described herein, e.g. any of those compositions described immediately above. A piece of woven or non-woven fabric or sponge carrying, preferably impregnated with, a dilute form of the composition may be referred to as a wipe. The fabric or sponge may be formed of natural or man-made materials or a combination thereof. The woven fabric may be cotton, wool, hemp, silk, polyester, polypropylene, nylon and the like. The non-woven fabric is preferably cellulosic, and / or comprising polyester, polypropylene, as the like. The impregnation of the fabric or sponge may be achieved in a single step or a plurality of steps. The compositions of the invention may be added to the fabric or sponge, the fabric or sponge may be added to the compositions or each element may be combined simultaneously. “% w / w” (or “percentage weight by weight”, or wt%) is a commonly used expression designating the proportion of a composition that is made up of the compound in question. 1% w / w equates to 1 gram of compound per 100grams of composition, 2% w / w equates to 2g of compound per 100g of composition, and so on. 1% w / w also equates to 10 gram of compound per kilogram of composition. As used herein, the term “antimicrobial” means the ability of an agent to kill, destroy, or inhibit the growth of, microorganisms. This may therefore be a microbicidal activity and / or a microbiostatic activity. More particularly, the term "microbicidal" means the ability negatively to impact the viability (i.e. to reduce or inhibit or ablate the viability) of a microorganism. In particular, "microbicidal" means the ability to kill or destroy a microorganism. The terms "kill" and "destroy" encompass the complete or partial destruction of the microorganism, e.g. the full or partial disintegration of the cellular structure of a microorganism. A microbicidal agent or substance is one has the capability of rendering a microorganism nonviable and unable to cause infections or reproduce. "Microbiostatic" means the ability to inhibit the growth or activity of a microorganism. This may be temporary. As described further below, the term "growth" is used broadly herein to refer to any aspect of growth of a microorganism, including both an increase in size or in the numbers of a microorganism. The term "growth" thus explicitly includes replication or reproduction of a microorganism. The term “activity” includes causing infectious disease or spoilage. The term "inhibit" includes any degree of reduction of growth or activity (as compared for example to growth or activity which may be observed in the absence of the microbiostatic agent) as well prevention of growth or activity. The term "microbicidal" thus includes a cytotoxic effect of an agent against a microorganism. Therefore, a microbicidal agent can be viewed as bactericidal, fungicidal (e.g. yeasticidal), algicidal, protozoacidal and so on depending on the type of microorganism that the agent is cytotoxic against. Similarly, the term "microbiostatic" can be viewed as a reference to a cytostatic effect of an agent against a microorganism. Therefore, in relation to the term "microbe" a microbiostatic agent can be categorised as bacteriostatic, fungistatic (e.g. yeastistatic), algistatic, protozoastatic and so on depending on the type of microbe that the agent is cytostatic against. The term "viability of a microorganism" means the ability of a microbe to survive under given conditions. Survival can be considered equivalent to remaining alive. Determining the viability of a microorganism can be done using the techniques detailed below for measuring microorganism cell death (and viability). The term "killing a microorganism" refers to the act of causing a microorganism to cease to be alive, i.e. to become dead. A microorganism is considered to be alive if it can be induced to replicate and / or grow, or at least display morphological changes, when placed in a medium that would normally support the growth of that microorganism and / or the microorganism is metabolising nutrients to release energy to support cellular functions. Typically, a microorganism can be considered to be dead if cell membrane integrity is lost. Many routine assays are available to determine if a microorganism is alive (viable) or dead. One option is to place the microorganism in conditions that would normally support the growth of that microorganism and monitor the growth of the microorganism by appropriate standard means, e.g. by monitoring the size of the colony, the morphology of the microorganism, the number of colony forming unit / ml over time, the consumption of nutrients in the culture media, etc. Another option is to assess the microorganism for morphologies characteristic of cell death, e.g. necrotic or apoptotic bodies, membrane blebs, nuclear condensation and cleavage of DNA into regularly sized fragments, ruptured cell walls or membranes and leakage of cell contents into the extracellular environment. Other methods exploit the characteristic loss of cell membrane integrity in dead microorganisms. Membrane impermeable dyes (e.g. trypan blue and propidium iodide) are routinely used to assess membrane integrity. A still further option is to measure the metabolism of the microorganism. This can be done routinely in a number of ways. For instance, the levels of ATP can be measured By "growth of a microorganism" it is meant both an increase in the size of the microorganism or colonies thereof, or in the amount and / or volume of the constituents of a microorganism (e.g. the amount of nucleic acid, the amount of protein, the number of nuclei, the numbers or size of organelles, the volume of cytoplasm) and an increase in the numbers of a microorganism i.e. an increase in the replication of a microorganism. By "inhibiting the growth of a microorganism" it is meant that measurable growth (e.g. replication) of a microorganism or colony thereof, or the rate thereof, is reduced. Preferably measurable growth (e.g. replication) of a microorganism or colony, or the rate thereof, is reduced by at least 80%, more preferably at least 90%, 95%, 99%, 99.9% or 99.99%, e.g. at least 99.9%. Preferably, measurable growth (e.g. replication) is ceased. Growth in terms of microbial size increase or expansion etc. may be inhibited independently of replication and vice versa. In particular embodiments the compositions of the invention, or the fraction of active components thereof, are considered antimicrobial if they can achieve a log reduction in colony number of a target microorganism of at least 2, e.g. at least 2.2, 2.4, 2.6, 2.8, 3, 3.2, 3.4, 3.6, 3.8 or 4, preferably a log reduction in colony number of a target microorganism of at least 3, at 24hrs from exposure, as compared to an untreated colony of the target microorganism. In these definitions the references to “microorganism” may be taken to be reference to any combination or all of Staphylococcus aureus, Escherichia coli, Pseudomonas aeruginosa, and Enterococcus hirae. The compositions of the invention, or the fraction of active components thereof, are considered to have residual efficacy, by which it is meant that a test composition is able to have antimicrobial effects (as defined above) against a target microorganism on a surface to which it and the target microorganism has been applied following at least one cycle of (i) dry abrasion, (ii) re-inoculation of the target organism, (iii) wet abrasion and (iv) re-inoculation of the target organism, preferably at least 2 of said cycles, more preferably at least 3 of said cycles. Preferably said antimicrobial effects are present at least 1,2, 3, 4, 5, 6, 9, 12, 15, 18, 21, or 24 hours following the completion of the final abrasion cycle. In other embodiments, said antimicrobial effects are present at least 1, 2, 3, 4, 5, 6, 9, 12, 15, 18, 21, or 24 hours following the initiation first abrasion cycle In certain embodiments the abrasion and re-inoculation cycle performed is the abrasion and re-inoculation cycle of the PAS 2424 protocol (PAS2424: 2014 Quantitative surface test for the evaluation of residual antimicrobial (bactericidal and / or yeasticidal) efficacy of liquid chemical disinfectants on hard non-porous surfaces - Test methods; ISBN978 0 580 84408 9). In other embodiments, the compositions of the invention, or the fraction of active components thereof, are considered to have residual efficacy if they can achieve a log reduction in colony number of a target microorganism of at least 2, e.g. at least 2.2, 2.4, 2.6, 2.8, 3, 3.2, 3.4, 3.6, 3.8 or 4, preferably a log reduction in colony number of a target microorganism of at least 3, at 24hrs from exposure, as compared to an untreated colony of the target microorganism, following the processing of the treated surface in accordance with the PAS 2424 protocol. In a still further aspect the invention provides a method of preparing a ready to use form of an antimicrobial aqueous liquid composition as described herein, said method comprising: (i) diluting a concentrated form of the ready to use composition with a sufficient amount of an aqueous diluent to form said ready to use antimicrobial aqueous composition, or (ii) dissolving a dry solid composition as described herein in with a sufficient amount of an aqueous liquid to form said ready to use antimicrobial aqueous composition. The above method may further comprise a step in which the ready to use antimicrobial aqueous composition is used in a method of combating contamination of a site with a microorganism, e.g. those methods described in detail below. Any appropriate aqueous diluent may be used to achieve the required dilution of the antimicrobial liquid compositions described herein. In preferred embodiments, the aqueous diluent is water, or a an aqueous solution or suspension carrying the above described carriers, excipients or diluents in amounts permitted by the parameters of the invention disclosed herein. In particular the diluent may comprise organic or inorganic salts, pH buffers, acids and / or alkalis. Most conveniently, the diluent is water, in particular purified water. As used herein, the term “sufficient amount of aqueous diluent” is taken to mean that the amount of aqueous diluent used to dilute the antimicrobial liquid composition of the invention is sufficient to achieve a dilution of about 100x, 50x, 40x, 30x, 20x, 19x, 18x, 17x, 16x, 15x, 14x, 13x, 12x, 11x, 10x or about 5x. Preferably, the dilution achieved is about 30x to about 20x, most preferably about 20x. Expressed differently, the antimicrobial liquid composition of the invention is diluted to about 10%, 9%, 8%, 7%, 6%, 5%, 4%, 3%, 2%, or about 1% or less. Preferably, the antimicrobial liquid composition of the invention is diluted to about 5%. The dilution of the concentrated form of the antimicrobial aqueous composition and the dissolution of the dry solid composition may be achieved in a single step or a plurality of steps. The compositions may be added to the aqueous diluent / liquid, the aqueous diluent / liquid may be added to the compositions or each element may be combined simultaneously. In embodiments where a plurality of steps is employed, these may be additive / cumulative (repeated addition of aqueous diluent / liquid to the compositions, or portion thereof) or serial (repeated addition of the mixture of composition and aqueous diluent / liquid, or portion thereof, to more diluent / liquid) or a combination thereof. Preferably dilution is achieved in less than 10 steps, e.g. less than 9, 8, 7, 6, 5, 4, or 3 steps. More preferably dilution is achieved in 2 steps or, most conveniently, a single step. In another aspect, the invention also provides a method for combating contamination of a site with a microorganism, said method comprising contacting the site and / or the microorganism with the antimicrobial liquid composition of the invention (which term includes an antimicrobial liquid composition of the invention as defined herein, a diluted (i.e. “ready to use”) form thereof, or a composition comprising the same). For the sake of brevity, in the following, references to an antimicrobial composition of the invention are interchangeable with references to an antimicrobial liquid composition of the invention as defined herein, a diluted (i.e. “ready to use”) form thereof, or a composition (e.g. a biocidal or pharmaceutical composition) comprising the same. "Combating contamination" includes both preventative and reactionary measures or treatments and therefore covers the prevention as well as the reduction, limitation, inhibition or elimination of contamination. The term may be considered to cover “sanitising”, “disinfecting” or “sterilising” measures or treatments. To disinfect or to sanitise is to reduce levels of microbes to those considered safe by local public health ordinance over a preselected timeframe, e.g. 24hrs. To sterilise is to eliminate microbes over a preselected timeframe, e.g. 24hrs. By "contamination" it is meant the unwanted presence of a microorganism at a particular site or location. In abiotic locations this can be considered at its extreme to refer to the presence of any microorganism at the site. Contamination can be considered to cover colonisation of a location by the microorganism, i.e. the establishment of a microorganism at a location and the expansion of the numbers of that microorganism by replication or the recruitment of additional microorganisms, which may be of the same or of a different type. More particularly the site (or location) and / or microorganism (or colony thereof) will be contacted with an effective amount of the antimicrobial aqueous liquid composition, more particularly an amount of the antimicrobial aqueous liquid composition sufficient to kill or inhibit the growth of the microorganism (or colony thereof). More preferably an amount sufficient to provide persistent antimicrobial effects as defined herein, more preferably to display residual efficacy as defined herein. Expressed differently, the site may be considered to be “sanitised”, “disinfected” or “sterilised”. Colonisation or contamination may be prevented therefore over a prolonged period of time, e.g. as defined herein. The site or location of the microorganism is not restricted. The microorganism may be present on a surface. The surface is not limited and includes any surface on which a microorganism may occur. The surface may be biotic or abiotic, and inanimate (or abiotic) surfaces include any such surface which may be exposed to microbial contact or contamination. Thus, particularly included are domestic (e.g. surfaces in kitchens, lavatory, washroom and utility areas) as well as large-scale industrial, agricultural, clinical and commercial surfaces, e.g. those on machinery, notably industrial machinery, or medical equipment or any surface exposed to an aquatic environment (e.g. marine equipment, or ships or boats or their parts or components), or any surface exposed to any part of the environment, e.g. pipes or on buildings. Such inanimate surfaces exposed to microbial contact or contamination include in particular any part of: food or drink processing, preparation, storage or dispensing machinery or equipment (in particular meat processing machinery or equipment and abattoir machinery or equipment, but also fruit and vegetable processing machinery or equipment), surfaces exposed to human or animal touch (e.g. door furniture, switches, touchscreens, touchpads, keyboards, machine controls, taps, and sanitaryware), air conditioning apparatus, industrial machinery, e.g. in chemical or biotechnological processing plants, storage tanks, medical or surgical equipment and cell and tissue culture equipment. Any apparatus or equipment for carrying or transporting or delivering materials is susceptible to microbial contamination. Such surfaces will include particularly pipes (which term is used broadly herein to include any conduit or line). Representative inanimate or abiotic surfaces include, but are not limited to food processing, storage, dispensing or preparation equipment or surfaces, tanks, conveyors, floors, drains, coolers, freezers, equipment surfaces, walls, valves, belts, pipes, air conditioning conduits, cooling apparatus, food or drink dispensing lines, heat exchangers, boat hulls or any part of a boat's structure that is exposed to water, dental waterlines, oil drilling conduits, contact lenses and storage cases. Medical or surgical equipment or devices represent a particular class of surface on which microbial contamination may form. This may include any kind of line, including catheters (e.g. central venous and urinary catheters), prosthetic devices e.g., heart valves, artificial joints, false teeth, dental crowns, dental caps and soft tissue implants (e.g. breast, buttock and lip implants). Any kind of implantable (or "in-dwelling") medical device is included (e.g. stents, intrauterine devices, pacemakers, intubation tubes (e.g. endotracheal or tracheostomy tubes), prostheses or prosthetic devices, lines or catheters). An "in-dwelling" medical device may include a device in which any part of it is contained within the body, i.e. the device may be wholly or partly in-dwelling. The surface can be made of any material, although typical it will be a hard and / or substantially non-absorbent surface. For example, it may be metal, e.g. aluminium, steel, stainless steel, chrome, titanium, iron, alloys thereof, and the like. The surface can also be plastic, for example, polyolefin (e.g., polyethylene, (Ultra-High Molecular Weight) polyethylene, polypropylene, polystyrene, poly(meth)acrylate, acrylonitrile, butadiene, ABS, acrylonitrile butadiene, etc.), polyester (e.g., polyethylene terephthalate, etc.), and polyamide (e.g., nylon), combinations thereof, and the like. Other examples include acetal copolymer, polyphenylsulfone, polysulfone, polythermide, polycarbonate, polyetheretherketone, polyvinylidene fluoride, poly(methyl methacrylate) and poly(tetrafluoroethylene). The surface can also be silicon, brick, tile, ceramic, porcelain, wood, vinyl, linoleum, combinations thereof, and the like. The surfaces can also be food, for example, beef, poultry, pork, vegetables, fruits, fish, shellfish, combinations thereof, and the like. Foodstuffs, such as those described above, in isolation from an animal or plant body, are considered inanimate for the purposes of the invention. A biotic or animate surface may include any surface or interface in or on an animal, plant or fungal body. It may accordingly be viewed as a "physiological" or "biological" surface. It may be any internal or external body surface, including of any tissue or organ, which, in the case of an animal body, may include haematological or haematopoietic tissue (e.g. blood). Dead or dying (e.g. necrotic) or damaged (e.g. inflamed or disrupted or broken) tissue is particularly susceptible to microbiological contamination, and such tissue is encompassed by the term "animate" or "biotic". The surface may be a mucosal or non-mucosal surface. Representative biotic surfaces include, but are not limited to, any surface in the oral cavity (e.g. teeth, gingiva, gingival crevice, periodontal pocket) the reproductive tract (e.g. cervix, uterus, fallopian tubes), the peritoneum, middle ear, prostate, urinary tract, vascular intima, eye, i.e. ocular tissue (e.g. the conjunctiva lachrymal duct, lachrymal gland, eyelid), corneal tissue, the respiratory tract, lung tissue (e.g. bronchial and alveolar), heart valves, gastrointestinal tract, skin, scalp, nails and the interior of wounds, particularly chronic wounds and surgical wounds, which may be topical or internal wounds. Other surfaces include the exterior of organs, particularly those undergoing transplantation, for example, heart, lungs, kidney, liver, heart valve, pancreas, intestine, corneal tissue, arterial and venous grafts and skin. Skin, wounds and transplant tissue are of note. As will be clear from the foregoing, the site or location of the contamination or potential contamination is not restricted, e.g. it can be in vitro or in vivo, but particularly in this aspect of the invention it will be an "in vitro" or "ex vivo" site or location (i.e. an inanimate or abiotic site or location, or an animate or biotic site or location that is isolated from (not in or on) a human, animal, plant or fungal body). However, the site or location may be in or on a human or animal subject and in which case a therapeutically effective amount of the antimicrobial composition is administered to the subject. Where the use to which the antimicrobial aqueous composition is put is in the combat of microbial contamination on an inanimate surface in vitro, i.e. not on or in a living human or animal body, the antimicrobial aqueous composition may be applied to the surface to be treated by any convenient means. For instance, a liquid form of the antimicrobial aqueous composition of the invention may simply be sprayed onto the inanimate surface to be treated, e.g. via a misting system or via a spray gun or other atomising device which may be manual, semi-automated or fully automated. Spraying may involve a propellant but preferably will be propellant free. Spray applications may involve a pre- and / or post application spraying of water or other aqueous solution. In other examples a liquid or gel form of the antimicrobial aqueous composition of the invention may be applied and spread with an appropriate implement or device, e.g. via a fabric or sponge wipe carrying the composition. A typical misting system / infrastructure (which terms are used interchangeably) of use in accordance with the invention may comprise a spray nozzle (also referred to as an atomiser or a nebuliser) to which the ready to use aqueous liquid composition of use in the invention is delivered at sufficient pressure to atomise the liquid thereby producing a spray (mist) of suitable droplet size to effect successful administration / application to the treatment site and a remote reservoir of the liquid to be sprayed. Delivery of the liquid to the nozzle is typically via conduits (e.g. pipes, hosing, tubing or waterlines). In other embodiments a reservoir of a concentrated liquid form or dry solid form of the aqueous liquid composition of the invention is provided and dilution of that composition with a suitable aqueous diluent, e.g. water, is takes place in a separate reservoir or in the conduit between the reservoir of a concentrated aqueous liquid composition and the spray nozzle. Thus, a preferred misting system of the invention may comprise a nozzle, a reservoir adapted to contain a concentrated aqueous liquid composition of the invention, a conduit between the reservoir and the nozzle and means for delivering a suitable aqueous solvent to the concentrated aqueous liquid composition prior to its expulsion through the nozzle. The misting system may have a further reservoir adapted to contain the aqueous solvent. The misting system may be integrated within a building or structure or be free-standing. The misting system may be manual, semi-automated or automated. The misting system may therefore be controlled by a computer program and thus a further component of a misting system of use in the invention may be a computer, system or apparatus carrying a program adapted to control the misting system, preferably adapted to perform an automated or semi-automated misting protocol. Thus in a further aspect the invention provides a misting system, specifically a residual misting system (i.e. a system that provides a spray that leaves a residue on a treatment site) containing one or more spray nozzles, a first reservoir and a conduit between the first reservoir and the spray nozzles adapted to convey the contents of the first reservoir to the spray nozzle, wherein the misting system, or portion thereof (e.g. said first reservoir) contains an antimicrobial aqueous composition of the invention as defined herein. In preferred embodiments the misting system further comprises the means to deliver an aqueous diluent to the first reservoir, a mixing receptacle, the conduit or the nozzle thereby diluting at least a portion of the contents of the first reservoir. In further embodiments the misting system further comprises a second reservoir containing a suitable aqueous solvent. In still further embodiments the misting system further comprises a computer, system or apparatus carrying a program adapted to control the misting system, preferably adapted to perform an automated or semi-automated misting protocol. A suitable misting system is disclosed in PCT / IB2023 / 051987. Also provided is an antimicrobial aqueous liquid composition as defined above for use in inhibiting the viability and / or growth of a microorganism in or on a subject. Alternatively put, this aspect of the invention provides the use of an antimicrobial aqueous liquid composition as defined above, for the manufacture of a medicament for inhibiting the viability and / or growth of a microorganism in or on a subject. This aspect of the invention also provides the use of the above recited components of the antimicrobial aqueous liquid composition as defined above for the manufacture of an antimicrobial liquid composition as defined above for inhibiting the viability and / or growth of a microorganism in or on a subject. Viewed differently, in a further aspect, the invention also provides an antimicrobial aqueous liquid composition as defined herein for use as a therapeutic microbicidal and / or microbiostatic agent and the use of an antimicrobial aqueous liquid composition as defined herein for the manufacture of a microbicidal and / or a microbiostatic medicament having the features of the antimicrobial aqueous liquid composition as defined above. The invention also provides the use of the above recited components of the antimicrobial aqueous liquid composition as defined herein for the manufacture of a microbicidal and / or a microbiostatic medicament having the features of the antimicrobial liquid composition as defined herein. These aspects of the invention can also be seen to provide (i) a method for combating, and in particular in the treatment or prevention of, microbial infection in or on an subject said method comprising administering an effective amount of the antimicrobial aqueous liquid composition as defined above to a subject in need thereof; (ii) an antimicrobial aqueous liquid composition as defined above for use in combating, and in particular in the treatment or prevention of, microbial infection in or on an subject; (iii) the use of an antimicrobial aqueous liquid composition as defined above in the manufacture of a medicament for use in combating, and in particular in the treatment or prevention of, microbial infection in or on a subject or (iv) the use of the above recited components of the antimicrobial aqueous liquid composition as defined above in the manufacture of a medicament having the features of the antimicrobial liquid composition as defined above for use in combating, and in particular in the treatment or prevention of, microbial infection in or on a subject. It will be seen in this aspect that the infection may be combated by inhibiting the growth and / or viability of a microorganism in or on a subject. The term "microorganism" as used to describe the target of the above described methods and uses includes any microbial organism, that is any organism that is microscopic, namely too small to be seen by the naked eye. In particular as used herein the term includes the organisms typically thought of as microorganisms, particularly bacteria, fungi, archaea, algae and protists. The term thus particularly includes organisms that are typically unicellular, but which may have the capability of organising into simple cooperative colonies or structures such as filaments, hyphae or mycelia (but not true tissues) under certain conditions. The microorganism may be prokaryotic or eukaryotic, and may be from any class, genus or species of microorganism. Examples of prokaryotic microorganisms include, but are not limited to, bacteria, including the mycoplasmas, (e.g. Gram-positive, Gramnegative bacteria or Gram test non-responsive bacteria or mycobacteria) and archaeobacteria. Eukaryotic microorganisms include fungi, algae and others that are, or have been, classified in the taxonomic kingdom Protista or regarded as protists, and include, but are not limited to, for example, protozoa, diatoms, protoophyta, and fungus-like molds. The microorganism may be aerobic or anaerobic. The microorganism may be pathogenic or non-pathogenic, or a be spoilage or an indicator microorganism. In particular preferred embodiments the microorganism is pathogenic. Bacteria or fungi represent preferred classes of target microorganism. The target bacteria may be Gram positive or Gram negative bacteria, or indeed Gram-indeterminate bacteria. Within the Gram-negative bacteria the Enterobacteriaceae and the Gram-negative bacteria non-fermenting bacteria are of particular note. Preferably the target bacteria are selected from the following genera: Achromobacter, Acinetobacter, Actinobacillus, Aeromonas, Agrobacterium, Alcaligenes, Alteromonas. Bacteroides. Bartonella, Borrelia, Bordetella, Brucella, Burkholderia, Campylobacter, Cardiobacterium, Chlamydia, Chlamydophila, Chromobacterium, Chyseobacterium, Chryseomonas, Citrobacter, Clostridium, Comamonas, Corynebacterium, Coxiella, Cryptobacterium, Edwardsiella, Eikenella, Enterobacter, Enterococcus, Erwinia, Escherichia, Kingella, Klebsiella, Lactobacillus, Lactococcus, Legionella, Leptospira, Leptotrichia, Leuconostoc, Listeria, Listonella, Mobiluncus, Moraxella, Morganella, Mycobacterium, Mycoplasma, Neisseria, Nocardia, Nocardiopsis. Pantoea, Parachlamydia, Pasteurella, Peptococcus, Peptostreptococcus, Prevotella, Propionibacterium, Proteus, Providencia, Pseudomonas, Ralstonia, Rickettsia, Salmonella, Shewenella, Shigella, Sphingobacterium, Sphingomonas, Staphylococcus, Stenotrophomonas, Streptobacillus, Streptococcus, Streptomyces, Treponem and Yersinia. Particular mention may be made of bacteria from the genera Pseudomonas, Acinetobacter, Burkholderia, Escherichia, Klebsiella, Streptococcus, Enterococcus, Providencia, Moraxalla, Staphylococcus, e.g. Pseudomonas aeruginosa, Acinetobacter baumannii, Burkholderia spp, E. coli, Klebsiella pneumoniae, Burkholderia cepacia, Burkholderia multivorans, Burkholderia mallei, Burkholderia pseudomallei, Acinetobacter Iwoffii, Providencia stuartii, Providencia rettgeri, Providencia alcalifaciens, Klebsiella oxytoca, Pseudomonas anguilliseptica, Pseudomonas oryzihabitans, Pseudomonas plecoglossicida, Pseudomonas luteola, Moraxalla catarrhalis, Enterococcus faecium, Enterococcus faecalis, Enterococcus hirae, Streptococcus oralis, Staphylococcus aureus (e.g. MRSA). The target microorganism may also be a, or from a, fungus, including for example fungi that may be, or may have been, classified as protista, e.g. fungi from the genera Candida, Aspergillus, Pneumocystis, Penicillium and Fusarium. Representative fungal species include, but are not limited to, Candida albicans, Candida dubliniensis, Cryptococcus neoformans, Histoplama capsulatum, Aspergillus fumigatus, Coccidiodes immitis, Paracoccidiodes brasiliensis. Blastomyces dermitidis, Pneomocystis carnii, Penicillium marneffi, Alternaria alternate. The microorganism may also be an, or from an, alga, including for example algae that may be, or may have been, classified as protista. Representative algal species include Chaetophora, Chlorella protothecoides, Coleochaete scutata, Coleochaete soluta, Cyanidioschyzon merolae Aphanochaete, Gloeotaenium, Oedogonium, Oocystis, Oscillatoria, Paradoxia multisitia, Phormidium, Chroococcus, Aphanothece, Fragillaria, Cocconis, Navicula, Cymbella, Phaeodactylum as well as cyanobacteria (blue-green algae) and diatoms such as Nitzschia palea. In one embodiment of this aspect the target microorganism is in a biofilm. In a further aspect the invention provides products susceptible to microbial contamination / colonisation whose susceptible surfaces have been pretreated with the antimicrobial aqueous liquid compositions of the invention as defined herein. By "pretreated" it is meant that the susceptible surface is exposed to an antimicrobial aqueous liquid composition of the invention prior to an exposure to microorganism and that the crystalline particle persists on the surface for a duration sufficient to prevent contamination / colonisation by a microorganism for an appreciable duration of time. Preferably the antimicrobial aqueous liquid composition will persist for substantially the useful life of the surface, e.g. the pretreatment results in a substantially permanent coating of an antimicrobial aqueous liquid composition. Thus, a pre-treated surface / product is one to which the antimicrobial aqueous liquid composition is applied and on which it remains. Such a product / surface may be a coated product / surface. Non-limiting examples of products and surfaces susceptible to microbial contamination / colonisation are described above. Particular mention may be made of medical and surgical devices, food or drink processing, storage or dispensing equipment, in particular such equipment in meat processing plants and abattoirs, and food and drink stuffs, in particular meats, vegetables and fruits and processed products containing the same, surfaces susceptible to frequent human or animal touch (e.g. door furniture, switches, touchscreens, touchpads, keyboards, machine controls, taps, and sanitaryware). Pretreatment can be achieved by any convenient means, for example any form of applying the antimicrobial liquid composition to the surface, notably coating (e.g. spray coating) the surface, e.g. with an antimicrobial liquid composition of the invention, or a diluted (i.e. “ready to use”) form thereof. The invention will be further described with reference to the following non-limiting Examples in which: Figure 1 shows a flow-chart detailing the external PAS2424 screening methodology. Figure 2 shows the results of the PAS2424 external screening tests for sample numbers 14 and 15, in particular showing the log reduction against the test organism in each case. EXAMPLES Examplel - PAS2424 SCREENING Materials and Methods A variety of compositions were prepared in order to find and test compositions for residual efficacy according to the PAS2424 test. Table 1, below, provides details of the components used in the series of compositions synthesised. Abbreviation Trade Name Chemical Name Function % active agent in material used LA Lactic acid L-Lactic acid Active biocide 80% CA Citric acid Citric Acid pH regulator, chelator 100% F3000A (or F) Flosperse 3000 A Polyacrylic acid Anionic polymer surfactant 50% BT Bioterge AS40 HASB Sodium olefin sulfonate Anionic Surfactant 38% MV6 Surfaguard MV6 Maleic acid copolymer Anionic polymer surfactant 13% 5 Details of the various compositions created are provided below in Table 2, which sets out the amounts of each component material used in % w / w (the abbreviated names of the components are used in Table 2). 10 Sample Number LA CA F3000A BT MV6 Water Total 1 30% 0% 10% 0% 50% 10.00% 100% 2 40% 0% 10% 20% 20% 10.00% 100% 3 40% 0% 0% 30% 20% 10.00% 100% 4 40% 0% 10% 25% 20% 5.00% 100% 5 40% 0% 15% 30% 10% 5.00% 100% 6 40% 0% 15% 35% 7% 3.00% 100% 7 40% 0% 12% 40% 7% 1.00% 100% 8 40% 0% 0% 35% 20% 5.00% 100% 9 40% 0% 0% 40% 15% 5.00% 100% 10 40% 0% 20% 40% 0% 0.00% 100% 11 40% 0% 0% 20% 35% 5.00% 100% 12 50% 0% 0% 40% 10% 0.00% 100% 13 40% 3.5% 10% 20% 20% 6.00% 100% 14 40% 6% 10% 20% 20% 4.00% 100% 15 40% 3.5% 10% 15% 27% 4.50% 100% After a series of in-house screening experiments for both biocidal and potential residual efficacy using an in-house version of the PAS2424 test (data not shown), samples 14 and 15 showed particularly good and consistent performance in these areas and thus showed promise in terms of their ability to pass an external PAS2424 test for residual efficacy. Samples 14 and 15 were therefore sent off for an external PAS2424 screening test (TECOLAB SDN. BHD.). The external PAS2424 screening test protocol is summarised in Figure 1. Further details of the PAS2424:2014 protocol are provided in “Quantitative surface test for the evaluation of residual antimicrobial (bactericidal and / or yeasticidal) efficacy of liquid chemical disinfectants on hard non-porous surfaces - Test method” BSI Standards Publication, 2014, incorporated herein by reference. An overview of the PAS2424 test method from this publication is provided below. Overview of the PAS2424 test method: a) An initial inoculum of bacteria or yeast is applied to a steel disc and allowed to dry. This initial step simulates a contaminated surface before the application of a disinfectant product. b) A prepared sample of the test product (chemical disinfectant) is applied to the inoculated disc and allowed to dry. This gives a dried treatment which represents a surface that is likely to be exposed to abrasion and re-contamination before the next time it is treated with a disinfectant product. c) Over a period of 24 h the disc undergoes a series of abrasion cycles and reinoculations which are designed to simulate the abrasion and re-contamination (via touch and exposure) of a surface in between treatment with a disinfectant product. d) The disc is exposed to a final inoculum challenge (24 h after product application) under defined conditions for a specified contact time. The final inoculum challenge simulates an event that will promote the application of a disinfectant product. e) After the specified contact time the disc is transferred to a validated neutralizer solution so that the action of the residual disinfectant is quenched. The number of surviving organisms which can be recovered from the disc is determined quantitatively. f) The number of micro-organisms on a disc treated with hard water in place of disinfectant is also determined. The reduction in viable counts as a result of the residual product is calculated by the difference. In order to demonstrate residual efficacy the product shall give a >3 log reduction when challenged 24 h after 5 product application. More specific details on the PAS2424 test materials and methods followed for both the PAS2424 Standard tests (external) and an in-house screening method (used to screen the samples shown in Table 2 prior to any external testing of the most 10 promising candidates) are provided in Table 3, below. PAS 2424 Standard (external) In-house Screening Method TEST MATERIAL SPECIFK CATION Stainless steel discs Grade 304, 2B finish, both sides Grade 304, 2B finish, both sides Cut and prepared on-site using laser cutter Steel disc diameter 2cm and 1.5mm thick 2cm and 1.5mm thick Centrifuge weight 3.5cm centrifuge tube / weighing 210+ 2g 3.5cm centrifuge tube / weighing 210+ 2g Wipes for abrasion 100% Polypropylene 100% Polypropylene Sprayer for wet cycle Trigger spray bottle Trigger spray bottle Spray water Sterile hard water Sterile hard water Water for product dilution Sterile hard water (section 6.2.7) Tap water Interfering substance 3.0g / L for all inoculation 0.3g / L Stock cultures maintained In accordance with EN 12353 In accordance with EN 12353 TEST PREPARATION Working cultures (Inoculum preparation) Stock culture Master culture 1A working culture 2A working culture Stock culture Master culture 1A working culture 2A working culture Recently started preparing working cultures from Vitroids. Suspension inoculum 1.5 x 108 cfu / ml (1st &final inoculation) and 1.5 x 106 cfu / ml (reinoculation) 1.5- 1.9 x 108 cfu / ml (1st &final inoculation) 1.5- 1.9 x 106 cfu / ml (re-inoculation) adjusted using 0.5 McFarland Standard and Colorimeter Cultures for re-inoculation Kept at 2 - 8°C during test Kept at 2 - 8°C during test No. of disc / treatment 5 discs 5 discs for full method, 3 discs for quicker screening Neutraliser DE neutralising broth DE neutralising broth Spray distance of water &volume Using a trigger sprayer, spray the dry wipes twice from a disctance of ~75cm Wipes sprayed with spray bottle from a distance of ~75cm Diluent Tryptone sodium chloride solution (TSCS) TSCS Saline (0.85%) Final wipe thickness 4 sheets when folded 4 sheets when folded Stainless steel disc preparation Cleaned in de-ionised water and sterilised in 70% IPAfor atleast 15 mins. Clean &dried SSD autoclaved for 15 mins Cleaned in Protectus Viridis, thoroughly rinsed in de-ionised water and sterilised in 70% IPAfor at least 15 mins. Autoclaved for 15 mins Stainless steel disc Discarded once used Autoclaved and cleaned as above and re-used. TESTMETHI □D Step -1 SSD loaded with O.OImLof 1:1 inoculum mix (1.5 x 108 cfu / ml and 3g / L interfering substance) SSD loaded with 0.01mL of 1:1 inoculum mix (~ 108 cfu / ml and 0.3g / L interfering substance) Allow to dry Allow to dry Apply 0.1mL product Apply 0.1mL product Leave for 24hr Leave for 24hr Step - 2 1st Abrasion - dry wear 1st Abrasion - dry wear Re-inoculation Re-inoculation Spray wipe twice with hard water Spray wipe twice with sterile hard water Wet wear cycle Wet wear cycle Re-inoculate &dry Re-inoculate &dry Step - 3 2nd Abrasion - dry wear 2nd Abrasion - dry wear Re-inoculation Re-inoculation Spray wipe twice with hard water Spray wipe twice with sterile hard water Wet wear cycle Wet wear cycle Re-inoculate &dry Re-inoculate &dry Step - 4 3rd Abrasion - dry wear 3rd Abrasion - dry wear Re-inoculation Re-inoculation Spray wipe twice with hard water Spray wipe twice with sterile hard water Wet wear cycle Wet wear cycle Final inoculation Final inoculation RECOVERY &PLATI NG Incubation Incubation Count plates Count plates Re-incubation Re-incubation Record final result Record final result CONTROLS Control A Recovery of bacteria from surfaces (determine whether all bacteria has been recovered from discs in the test samples) Not always done Control B Neutraliser validation (determine whether neutraliser used has inactivated the product within the contact time) Not always done Control C Neutraliser toxicity (Demonstrate neutraliser is not toxic towards the organisms) Not always done Results Sample numbers 14 and 15 were sent to an external independent laboratory 5 (TECOLAB SDN. BHD.) for PAS2424 screening tests. The test organisms (E. hirae, S. aureus, E. coli and P. aeruginosa) were tested against a diluted composition with 1.6% Lactic acid, 0.3% Citric acid, 0.5% polyacrylic acid polymer (Flosperse 3000 A), 1% olefin sulfonate (Bioterge AS40 HASB) and 1% maleic acid copolymer surfactant (Surfaguard MV6) [diluted Sample 5 14] and a diluted composition with 1.6% Lactic acid, 0.18% Citric acid, 0.5% polyacrylic acid polymer (Flosperse 3000 A), 0.25% olefin sulfonate (Bioterge AS40 HASB) and 1.35% maleic acid copolymer surfactant (Surfaguard MV6) [Sample 15], Although sample numbers 14 and 15 had similar amounts of the various 10 components (see Table 1), sample 15 with increased amount of maleic acid copolymer surfactant surprisingly outperformed sample 14 against all of the test organisms and passed the PAS2424 screening test for residual efficacy. The results of the test are shown in Figure 2. 15 Sample 15 surpassed the target reduction in all of the organisms tested and thus shows great promise as an antimicrobial composition with residual (long-lasting) efficacy.

Claims

1. An antimicrobial aqueous liquid composition consisting of(i) equal to or greater than about 0.1 % w / w of an antimicrobial fraction consisting of Components (a) to (e)(ii) equal to or less than about 99.9% w / w water, and(iii) 0 to about 5% w / w diluents, excipients or carriers other than water, wherein the sum of the percentage amounts of (i), (ii) and (iii) is 100%, and wherein the total weight of the antimicrobial fraction in the composition consists of(a) about 60 to about 70% w / w lactic acid or a water-soluble salt thereof(b) about 4 to about 10% w / w citric acid or a water-soluble salt thereof(c) about 5 to about 15% w / w anionic polycarboxylate surfactant(d) about 9 to about 15% w / w a-Olefin (C12-C18) sulfonate(e) about 6 to about 10% w / w anionic maleic acid co-polymer surfactant.

2. The antimicrobial aqueous liquid composition of claim 1, wherein Component (a) is present in the antimicrobial fraction of the composition in an amount from about 63% w / w to about 65% w / w, or about 64 % w / w to about 65% w / w, preferably about 64% w / w.

3. The antimicrobial aqueous liquid composition of claim 1 or claim 2, wherein Component (b) is present in the antimicrobial fraction of the composition in an amount from about 6.0 % w / w to about 8.0% w / w, or about 6.5 % w / w to about 7.5% w / w, preferably about 7.0% w / w.

4. The antimicrobial aqueous liquid composition of any one of claims 1 to 3, wherein Component (c) is present in the composition in an amount from about 8 % w / w to about 12% w / w, or about 9 % w / w to about 11% w / w, about preferably10% w / w.11 10245. The antimicrobial aqueous liquid composition of any one of claims 1 to 4, wherein Component (d) is present in the antimicrobial fraction of the composition in an amount from about 10.5 % w / w to about 12.5% w / w, or about 11.0 % w / w to about 12.0% w / w, preferably about 11.5% w / w.

6. The antimicrobial aqueous liquid composition of any one of claims 1 to 5, wherein Component (e) is present in the antimicrobial fraction of the composition in an amount from about 6% w / w to about 8% w / w, or about 6.5% w / w to about 7.5% w / w, preferably about 7% w / w.

7. The antimicrobial aqueous liquid composition of any one of claims 1 to 6, wherein Component (c) is a homopolymer of acrylic acid, a homopolymer of maleic acid, a homopolymer of methacrylic acid, a heteropolymer of acrylic acid, maleic acid and / or methacrylic acid, a copolymer of acrylic acid, maleic acid and / or methacrylic acid, or homo- / hetero- / co-polymers of amino acids, or a water-soluble salt thereof.

8. The antimicrobial aqueous liquid composition of claim 7, wherein Component (c) is an acrylic acid homopolymer, maleic acid, maleic acid I acrylic acid copolymer, methacrylic acid homopolymer or acrylic acid I methacrylic acid copolymer.

9. The antimicrobial aqueous liquid composition of any one of claims 1 to 8, wherein Component (d) is an a-Olefin (C14-C16) sulfonate, preferably sodium a-Olefin (C14-C16) sulfonate.

10. The antimicrobial aqueous liquid composition of any one of claims 1 to 9,wherein Component (e) is methyl vinyl ether-maleic acid copolymer.

11. The antimicrobial aqueous liquid composition of any one of claims 1 to 10, wherein the antimicrobial aqueous liquid composition consists of(i) equal to or greater than 0.1 % w / w of an antimicrobial fraction consisting of components (a) to (e)(ii) equal to or less than 99.9% w / w water, and(iii) 0 to 5% w / w diluents, excipients or carriers other than water,11 1024wherein the sum of the percentage amounts of (i), (ii) and (iii) is 100%, and wherein the total weight of the antimicrobial fraction in the composition consists of(a) about 60 to about 70% w / w lactic acid or a water-soluble salt thereof(b) about 4 to about 10% w / w citric acid or a water-soluble salt thereof(c) about 5 to about 15% w / w polyacrylate(d) about 9 to about 15% w / w a-Olefin (C14-C16) sulfonate(e) about 6 to about 10% w / w methyl vinyl ether-maleic acid copolymer.

12. The antimicrobial aqueous liquid composition of any one of claims 1 to 11, wherein the antimicrobial fraction of the antimicrobial aqueous liquid composition amounts to(i) about 40 to about 60% w / w of the composition, water amounts to about 40 to about 60% w / w of the composition, and diluents, excipients or carriers other than water amount to 0 to about 5% w / w of the composition; or(ii) about 1 to about 5% w / w of the composition, water amounts to about 95 to about 99% w / w of the compositions and diluents, excipients or carriers other than water amount to 0% to about 0.5% w / w of the composition.

13. The antimicrobial aqueous liquid composition of any one of claims 1 to 12, wherein the antimicrobial aqueous liquid composition of the invention does not contain any diluents, excipients or carriers other than water.

14. The antimicrobial aqueous liquid composition of any one of claims 1 to 11, wherein the antimicrobial aqueous liquid composition consists of:(a) about 27 to about 37% w / w lactic acid or a water-soluble salt thereof(b) about 0.5 to about 6.5% w / w citric acid or a water-soluble salt thereof(c) about 1 to about 10% w / w anionic polycarboxylate surfactant(d) about 3 to about 8% w / w a-Olefin (C12-C18) sulfonate11 1024(e) about 2.5 to about 6.5% w / w anionic maleic acid co-polymer surfactant; and(f) about 32% to about 66% w / w water, wherein the sum of the percentage amounts of (a)-(f) is 100%.

15. The antimicrobial aqueous liquid composition of claim 14, wherein Component (a) is present in the composition in an amount from about 30% w / w to about 34% w / w, or about 31 % w / w to about 33% w / w, preferably about 32% w / w.

16. The antimicrobial aqueous liquid composition of claim 14 or claim 15, wherein Component (b) is present in the composition in an amount from about 2.5 % w / w to about 4.5% w / w, or about 3.0 % w / w to about 4.0% w / w, preferably about 3.5%.

17. The antimicrobial aqueous liquid composition of any one of claims 14 to 16, wherein Component (c) is present in the composition in an amount from about 3% w / w to about 7% w / w, or about 4% w / w to about 6% w / w, preferably about 5% w / w.

18. The antimicrobial aqueous liquid composition of any one of claims 14 to 17, wherein Component (d) is present in the composition in an amount from about 5.2 % w / w to about 6.2% w / w, or about 5.6 % w / w to about 5.8% w / w, preferably about 5.7% w / w.

19. The antimicrobial aqueous liquid composition of any one of claims 14 to 18, wherein Component (e) is present in the composition in an amount from about 2.5 % w / w to about 4.5% w / w, or about 3.0 % w / w to about 4.0% w / w, preferably about 3.5% w / w.

20. The antimicrobial aqueous liquid composition of any one of claims 14 to 19, wherein Component (f) is present in the composition in an amount from about 48% w / w to about 52% w / w, or about 49% w / w to about 51% w / w, preferably about 50% w / w.

21. The antimicrobial aqueous liquid composition of any one of claims 14 to 20, wherein the antimicrobial composition consists of:11 1024(a) 32% w / w lactic acid or a water-soluble salt thereof(b) 3.5% w / w citric acid or a water-soluble salt thereof(c) 5.0% w / w anionic polycarboxylate surfactant(d) 5.7% w / w a-Olefin (C12-C18) sulfonate(e) 3.51% w / w anionic maleic acid co-polymer surfactant; and(f) 50.29% w / w water.

22. The antimicrobial aqueous liquid composition of any one of claims 14 to 21, wherein the antimicrobial composition consists of:(a) 32% w / w lactic acid or a water-soluble salt thereof(b) 3.5% w / w citric acid or a water-soluble salt thereof(c) 5.0% w / w sodium polyacrylate(d) 5.7% w / w sodium a-Olefin (C14-C16) sulfonate(e) 3.51% w / w methyl vinyl ether-maleic acid copolymer; and(f) 50.29% w / w water.

23. The antimicrobial aqueous liquid composition of any one of claims 1 to 11, wherein the antimicrobial aqueous liquid composition consists of:(a) about 1.35 to about 1.75% w / w lactic acid or a water-soluble salt thereof(b) about 0.025 to about 0.325% w / w citric acid or a water-soluble salt thereof(c) about 0.05 to about 0.5% w / w anionic polycarboxylate surfactant(d) about 0.15 to about 0.4% w / w a-Olefin (C12-C18) sulfonate(e) about 0.125 to about 0.325% w / w anionic maleic acid co-polymer surfactant; and(f) about 96.7 to about 98.3% w / w water, wherein the sum of the percentage amounts of (a)-(f) is 100%.

24. The antimicrobial aqueous liquid composition of claim 23, wherein Component (a) is present in the composition in an amount from about 1.5% w / w to about 1.7% w / w, or about 1.55 % w / w to about 1.65% w / w, preferably about 1.6%.

25. The antimicrobial aqueous liquid composition of claim 23 or claim 24, wherein Component (b) is present in the composition in an amount from about11 10240.165% w / w to about 0.185% w / w, or about 0.170% w / w to about 0.180% w / w, preferably about 0.175% w / w.

26. The antimicrobial aqueous liquid composition of any one of claims 23 to 25, wherein Component (c) is present in the composition in an amount from about 0.15 % w / w to about 0.35% w / w, or about 0.2 % w / w to about 0.3% w / w, preferably about 0.25% w / w.

27. The antimicrobial aqueous liquid composition of any one of claims 23 to 26, wherein Component (d) is present in the composition in an amount from about 0.185% w / w to about 0.385% w / w, or about 0.235% w / w to about 0.335% w / w, about 0.285% w / w.

28. The antimicrobial aqueous liquid composition of any one of claims 23 to 27, wherein Component (e) is present in the composition in an amount from about 0.166% w / w to about 0.186% w / w, or about 0.171% w / w to about 0.181% w / w or about 0.174% w / w to about 0.178% w / w, preferably about 0.176% w / w.

29. The antimicrobial aqueous liquid composition of any one of claims 23 to 28, wherein Component (f) is present in the composition in an amount from about 97.0% w / w to about 98.0% w / w, or about 97.2% w / w to about 97.7% w / w, preferably about 97.5% or about 97.514%.

30. The antimicrobial aqueous liquid composition of any one of claims 23 to 29, wherein the antimicrobial composition consists of:(a) 1.6% w / w lactic acid or a water-soluble salt thereof(b) 0.175% w / w citric acid or a water-soluble salt thereof(c) 0.25% w / w anionic polycarboxylate surfactant(d) 0.285% w / w a-Olefin (C12-C18) sulfonate(e) 0.176% w / w anionic maleic acid co-polymer surfactant; and(f) 97.514% w / w water.

31. The antimicrobial aqueous liquid composition of any one of claims 23 to 30, wherein the antimicrobial composition consists of:(a) 1.6% w / w lactic acid or a water-soluble salt thereof11 1024(b) 0.175% w / w citric acid or a water-soluble salt thereof(c) 0.25% w / w sodium polyacrylate(d) 0.285% w / w sodium a-Olefin (Cu-Cw) sulfonate(e) 0.176% w / w methyl vinyl ether-maleic acid copolymer; and (f) 97.514% w / w water.

32. A woven or non-woven fabric or sponge carrying an antimicrobial aqueous liquid composition of any one of claims 23 to 30.

33. A method for combating contamination of a site with a microorganism, said method comprising contacting the site and / or the microorganism with the antimicrobial aqueous liquid composition of any one of claims 23 to 30.

34. The method of claim 33, wherein the antimicrobial aqueous liquid composition is applied to the site by the woven or non-woven fabric or sponge of claim 32 or by spray, atomiser or misting apparatus.

35. The method claims 33 or claim 34, wherein said site is, or the microorganism is on, an inanimate surface.

36. The method of claim 35, wherein the site is a surface selected from surfaces of food or drink processing, preparation, storage, packaging or dispensing machinery or equipment, abattoir machinery or equipment, fruit and vegetable processing or packaging machinery or equipment; surfaces of air conditioning apparatus; surfaces of industrial machinery, surfaces of storage tanks; surfaces of medical or surgical equipment; surfaces of clinical beds, furniture, floors, doors, door handles, operating theatres, office and IT equipment; cell and tissue culture equipment; surfaces of sanitaryware and fittings; surfaces of aquatic / marine equipment, the surfaces of buildings and other structures or the surfaces of food, preferably meat, fish, vegetables and fruit, and food packaging.

37. A product susceptible to microbial contamination comprising a surface which has been pretreated with the antimicrobial aqueous liquid composition as defined in any one of claims 1 to 31.11 102438. A kit comprising, optionally in separate containers:(i) lactic acid or a water-soluble salt thereof, optionally in an aqueous solution;(ii) citric acid or a water-soluble salt thereof, optionally in an aqueous solution;(iii) at least one anionic polycarboxylate surfactant, optionally in an aqueous solution,(iv) at least one a-Olefin (C12-C18) sulfonate, optionally in an aqueous solution,(v) at least one anionic maleic acid co-polymer surfactant, optionally in an aqueous solution, and(vi) instructions to prepare an antimicrobial aqueous liquid composition as defined in any one of claims 1-31, and optionally(vii) further components, e.g. excipients, carriers or other active agents, e.g. as defined herein.

39. A kit comprising:(i) a concentrated form of a ready to use antimicrobial aqueous liquid composition as defined in any one of claims 1-22, and(ii) instructions to prepare the ready to use form of the antimicrobial aqueous liquid composition as defined in any one of claims 23-31.

Images