DEVICE AND METHOD FOR OBTAINING A BIOLOGICAL SAMPLE FROM A SURFACE

Description

FIELD OF THE INVENTION

[0001] The invention pertains to an apparatus for and a method of obtaining a biological sample from a surface. More particularly, the invention pertains to an apparatus for and a method of obtaining a biological sample from an exposed surface of a human or animal body.BACKGROUND TO THE INVENTION

[0002] Infection of acute and chronic wounds presents a major impairment to wound healing. Most infected wounds are caused by bacterial colonization, originating either from the normal flora on the skin, or bacteria from other parts of the body or the outside environment.

[0003] In order to prescribe the correct treatment for the infected wound, a proper diagnostic assessment has to be performed. The diagnostic assessment is necessary to identify the causative organism (e.g., bacteria) of the infection.

[0004] It is known to analyse wound exudate to predict wound healing and to guide wound care. However, currently no biological assay exists to objectively assess wounds to aid in timing of wound closure and guide therapy. Changes in levels of proteases, protease inhibitors, and inflammatory markers have been correlated with wound healing. These findings further support the idea that inflammatory dysregulation and a persistent inflammatory state leads to failure of wound healing in the acute setting. These findings highlight potential targets for the development of a biological assay to individualize management of complex soft-tissue wounds, based on patient physiology and response, that would be applicable to not only military trauma but also civilian trauma. Ultimately, this would result in earlier wound closure, reduction in the number of operating room trips, and reduced health care costs. (Hahm, G., Glaser, JJ., Elster, EA. (2011) Biomarkers to predict wound healing: the future of complex war wound management. Plastic Reconstructive Surgery 127).

[0005] A biological marker (biomarker) is a substance used as an indicator of biological state. Advances in genomics, proteomics and molecular pathology have generated many candidate biomarkers with potential clinical value. Research has identified several cellular events and mediators associated with wound healing that can serve as biomarkers. Macrophages, neutrophils, fibroblasts and platelets release cytokines molecules including TNF-α, interleukins (ILs) and growth factors, of which platelet-derived growth factor (PDGF) holds the greatest importance. As a result, various white cells and connective tissue cells release both matrix metalloproteinases (MMPs) and the tissue inhibitors of metalloproteinases (TIMPs). Studies have demonstrated that IL-1, IL-6, and MMPs, levels above normal, and an abnormally high MMP / TIMP ratio are often present in non-healing wounds. Clinical examination of wounds for these mediators could predict which wounds will heal and which will not, suggesting use of these chemicals as biomarkers of wound healing. There is also evidence that the application of growth factors like PDGF will alleviate the recuperating process of chronic, non-healing wounds. Finding a specific biomarker for wound healing status would be a breakthrough in this field and helping treat impaired wound healing. (Patel, S., Maheshwari, A., Chandra, A. (2016); Biomarkers for wound healing and their evaluation - Wound Care (1):46-55).

[0006] The so-called swab-rinse technique is most often employed for the diagnostic assessment.

[0007] Conventional swabs used in the swab-rinse technique are made from a wooden or plastic shaft with cotton fibres spun to form a bud at one end of the shaft. In performing the swab-rinse technique, the bud is rubbed over the surface of the wound so as to remove bacteria. The bud may, optionally, be moistened in an appropriate wetting agent. Bacteria are then removed from the bud and transferred directly to a solid nutrient medium to develop a laboratory culture. The laboratory culture is then used to identify the causative organism.

[0008] The effectiveness of the above-described technique depends, amongst other things, on: (i) the removal of bacteria from the surface of the wound; (ii) the release of the bacteria from the bud of the swab; and (iii) the cultivation of the bacteria.

[0009] The above-described technique works only if the swab was performed properly.

[0010] It is known that swabbing efficacy is often poor. Studies have reported bacterial recovery rates ranging from 25% to just 0.1% of the original inoculum (Niskanen and Pohja 1977; Roelofsen et al. 1999; Moore and Griffith 2002; Taku et al. 2002; Obee et al. 2004).

[0011] Among the reasons for the poor efficacy of conventional swabbing techniques are inadequate training of a user taking the swab, ineffective absorption and adsorption capability of the bud of the swab and ineffective release of the bacteria from the bud of the swab.

[0012] GB2506010 describes microneedle-based devices and methods for the removal of fluid from the body, in particular interstitial fluid, using arrays of hollow or porous microneedles connected to a high-capacity absorbent material such as superabsorbent hydrogel and microporous materials, including porous silica within a pouch or windowed dressing. The system is primarily aimed at therapeutic fluid extraction, such as renal replacement therapy, treatment of oedema and heart failure under negative pressure, rather than non-invasive sampling of wound exudate using a sachet of discrete ceramic particles.

[0013] EP2523605 A1 describes a device for transiently contacting at least one capture unit with a body fluid, in which a sampling tip, such as a catheter or needle, carries a capture substrate covered with a biocompatible porous polymer gel layer that retains functionalised nanoparticles and allows biological targets to diffuse in from circulating fluids like blood, cerebrospinal fluid or interstitial fluid. After contact, the gel is dissolved, and the particles recovered, typically magnetically, for analysis.

[0014] US 2004 / 0193030 A1 relates to body-fluid collection and analysis using a storage element formed of porous silicon or similar porous media held beneath a cover or dressing and placed against the skin or another body surface, for example, to collect sweat or other excreted fluids over time. The collected analytes are then analysed, particularly by mass-spectrometric techniques, based on their accumulation in the porous silicon.OBJECT OF THE INVENTION

[0015] It is an object of the present invention to provide an apparatus for and a method of obtaining a biological sample from an exposed surface of a human or animal body with which the applicant believes the above disadvantages may at least be alleviated or which will provide a useful alternative to known apparatuses and methods.SUMMARY OF THE INVENTION

[0016] The invention is defined by the independent claims. Preferred features are defined in the dependent claims.DETAILED DESCRIPTION OF THE INVENTION

[0017] The plurality of separate and porous ceramic particles may be formed by a method including the steps of: (i) milling alumina (Al 2 O 3 ) into a powder consisting of particles having a diameter of approximately 1 micrometre; (ii) adding a combustible substance to the powder; (iii) mixing the powder with water to form a paste or slurry; (iv) forming of particles from paste or slurry to separate particles having a diameter of between 300 and 3000 micrometres; and (v) heating the ceramic aggregate to a temperature of 1200°C to form an inert microporous solid ceramic body having pore sizes of between 0.3 and 30 micrometres.

[0018] Each of the plurality of separate and porous ceramic particles has a diameter of between 30 and 3000 micrometres, are inert and have a porosity of between 25% and 85%.

[0019] The pores of the plurality of separate and porous ceramic particles are cellular in nature and have a diameter of between 0.3 and 30 micrometres. The pores are interconnected to one another by means of blow-holes, which form when the combustible substance escapes from the ceramic aggregate when the latter melts at or close to 1200°C.

[0020] A plurality of the separate and porous ceramic particles is encased in a liquid and gas permeable sachet to form an apparatus for obtaining a biological sample from an exposed surface of a human or animal body (e.g., a wound). The sachet is a sterile sachet and the separate and porous ceramic particles are packed loosely therein so as to allow air to pervade therethrough. The sachet is formed from an organic, non-woven material.

[0021] The plurality of separate and porous ceramic particles has a relatively large surface area and their micro-pores exhibit a significant capillary suction force.

[0022] In use, when the apparatus makes contact with the wound of the human or animal body, the plurality of separate and porous ceramic particles exert a capillary suction force on biological material present on the surface of the wound. The biological material is then absorbed, transported and stored in the micro-pores of the plurality of separate and porous ceramic particles. Since each separate and porous ceramic particle is in contact with surrounding particles of the same kind, biological material on the surface of the wound of the human or animal body migrates continuously between the particles to equalize the hydrostatic potential of all the separate and porous ceramic particles in the sachet. There is no driving force for the biological material to leave the micro-pores of the separate and porous ceramic particles. In this manner, a biological sample is obtained from the wound of the human or animal body.

[0023] As discussed above, each of the plurality of separate and porous ceramic particles is made from alumina (Al 2 O 3 ). The surfaces of the plurality of alumina (Al 2 O 3 ) particles are highly charged. The surfaces of the alumina (Al 2 O 3 ) particles are relatively rough and have a wetting angle of 0°. Therefore, the alumina particles are easily wetted. The alumina (Al 2 O 3 ) particles typically have a surface area of 0.5 m 2< per gram of alumina (Al 2 O 3 ). Each gram of alumina (Al 2 O 3 ) comprises 3.5 x 10 21< oxygen ions (O 2-< ) and 2.4 x 10 21< aluminium ions (Al 3+< ), a fair portion of which are exposed to the surface of the particles.

[0024] It is known that every cell in a living organism contains an electrical charge defined as the difference between charged atoms on either side of the cell's membrane. A proton colloidal solid, on the other hand, may develop a surface charge due to the ionization of side-chain amino acid groups.

[0025] In use, when the plurality of separate and porous alumina particles comes into contact with biological material from the wound, the highly charged alumina surfaces (5.9 x 10 21< ionic charges per gram) are continuously wetted by biological material. The surfaces of the plurality of separate and porous alumina particles are rough and ideal for adsorbing charged colloidal cells, microorganism, biomarkers, deoxyribonucleic acid (DNA) molecules, proteins, and endotoxins and the like to adhere thereto. Adhesion is caused by ionic and electrostatic interactions, hydrogen bonding and charge-transfer interactions. In this manner, strong adsorption takes place and a biological sample is obtained from the wound of the human or animal body.

[0026] The biological material includes wound exudate containing any one or more selected from the group consisting of microorganisms, biomarkers, deoxyribonucleic acid (DNA), proteins, cellular molecules, endotoxins or combinations thereof, macrophages, neutrophils, fibroblasts, platelets, cytokines molecules including TNF-α, interleukins (ILs) and growth factors, including platelet-derived growth factor (PDGF), matrix metalloproteinases (MMPs), tissue inhibitors of metalloproteinases (TIMPs), IL-1, IL-6, and MMPs, proteases, protease inhibitors, and inflammatory markers, and the microorganisms include any one or more selected from the group consisting of bacteria, viruses, fungi and parasites.

[0027] The apparatus for obtaining a biological sample from an exposed surface (e.g., a wound) of a human or animal body may include an adhesive dressing. When the apparatus is removed from the wound, the biological material siphoned off from the wound locates in the micro-pores as well as on the surfaces of the plurality of separate and porous ceramic particles. This biological material then forms the biological sample obtained from the wound.

[0028] The biological sample obtained from the wound is subjected to sonication to disintegrate a biofilm of microorganisms (e.g., bacteria) present in the biological sample and to form a sonication fluid containing microorganisms. Sonication is typically performed at frequencies of 20 kilohertz. The sonication fluid containing microorganisms is then used to cultivate microorganisms for identifying microorganisms present in the sonication fluid containing microorganisms. These microorganisms are typically bacteria and by cultivating the bacteria the different strains of bacteria present in the sonication fluid can be identified. This enables a healthcare practitioner to prescribe the correct treatment for an infected wound of a human or animal patient.

[0029] The sonication fluid can also be used to identify biomarkers which are indicative of the stage of wound healing. This will further inform a healthcare practitioner to prescribe the correct treatment for an infected wound of a human or animal patient.

[0030] It was found that the biological sample obtained from the wound could be analysed to predict wound healing and to guide wound care. In particular, analysing the levels of macrophages, neutrophils, fibroblasts, platelets, cytokines molecules including TNF-α, interleukins (ILs) and growth factors, including platelet-derived growth factor (PDGF), matrix metalloproteinases (MMPs), tissue inhibitors of metalloproteinases (TIMPs), IL-1, IL-6, and MMPs, proteases, protease inhibitors, and inflammatory markers, provide useful insight to wound care specialists on the status of the wound healing process and assist in predicting progress and prescribing the appropriate treatment regime.

[0031] It will be appreciated by those skilled in the art that the invention is not limited to the precise details as described herein and that many variations are possible without departing from the scope of the invention. The scope of the invention is defined by the appended claims solely.

[0032] The description is presented by way of example only in the cause of providing what is believed to be the most useful and readily understood description of the principles and conceptual aspects of the invention. In this regard, no attempt is made to show more detail than is necessary for a fundamental understanding of the invention. The words which have been used herein are words of description and illustration, rather than words of limitation.REFERENCES

[0033] Hahm, G., Glaser, JJ., Elster, EA. (2011) Biomarkers to predict wound healing: the future of complex war wound management. Plastic Reconstructive Surgery 127. Moore, G. and Griffith, C. (2002) Factors influencing recovery of microorganisms from surfaces by use of traditional hygiene swabbing. Dairy Food Environ Sanit 22, 14- 25. Niskanen, A. and Pohja, M.S. (1977) Comparative studies on the sampling and investigation of microbial contamination of surfaces by the contact plate and swab methods. J Appl Bacteriol 42, 53- 63. Roelofsen, E., Van Leeuwen, M., Meijer-Severs, G.J., Wilkinson, M.H.F. and Degener, J.E. (1999) Evaluation of the effects of storage in two different swab fabrics and under three different transport conditions on recovery of aerobic and anaerobic bacteria. J Clin Microbiol 37, 3041- 3043. Obee, P., Griffith, C., Cooper, R., Bennion, N. and Ramsey, C. (2004) Recovery of methicillin resistant Staphylococcus aureus (MRSA) from wet and dry environmental surfaces. American Society for Microbiology, 104th General Meeting. New Orleans, 23- 27 May, 2004. Patel, S., Maheshwari, A., Chandra, A. (2016); Biomarkers for wound healing and their evaluation. Wound Care (1):46-55. Taku, A., Gulati, B.R., Allwood, P.B., Palazzi, K., Hedberg, C.W. and Goyal, S.M. (2002) Concentration and detection of caliciviruses from food contact surfaces. J Food Prot 65, 999- 1004.

Claims

1. An apparatus for obtaining a biological sample from an exposed surface of a human or animal body, the apparatus including a plurality of separate and porous ceramic particles for absorbing and adsorbing biological material from the exposed surface; and a permeable covering for containing the plurality of separate and porous ceramic particles, wherein the biological material having been absorbed and adsorbed by the plurality of separate and porous ceramic particles forms the biological sample, wherein the plurality of separate and porous ceramic particles have a diameter of between 300 and 3000 micrometres, and wherein the plurality of separate and porous ceramic particles have a charged surface caused by ionic and electrostatic interaction, hydrogen bonding and charge-transfer interactions.

2. The apparatus according to claim 1, wherein the plurality of separate and porous ceramic particles are inert and have a porosity of between 25% and 85%.

3. The apparatus according to claim 1, wherein the plurality of separate and porous ceramic particles have pores with a diameter of between 0.3 and 30 micrometres and wherein the pores are cellular in nature and are interconnected with one another by means of blow-holes.

4. The apparatus according to claim 1, wherein the permeable covering is in the form of a sterile permeable and wettable sachet formed from an organic, non-woven material.

5. A method of obtaining a biological sample from an exposed skin surface or external wound of a human or animal body, the method including the steps of providing an apparatus according to any one of claims 1 to 4; and contacting the apparatus with the exposed skin surface or external wound to permit the plurality of separate and porous ceramic particles to absorb and adsorb biological material from the exposed surface, wherein the biological material having been absorbed and adsorbed by the plurality of separate and porous ceramic particles forms the biological sample.

6. The method according to claim 5, wherein the exposed surface is an external wound of a human or animal and the biological material includes wound exudate containing any one or more selected from the group consisting of microorganisms, biomarkers, deoxyribonucleic acid (DNA), proteins, cellular molecules, endotoxins or combinations thereof, macrophages, neutrophils, fibroblasts, platelets, cytokines molecules including TNF-α, interleukins (ILs) and growth factors, including platelet-derived growth factor (PDGF), matrix metalloproteinases (MMPs), tissue inhibitors of metalloproteinases (TIMPs), IL-1, IL-6, and MMPs, proteases, protease inhibitors, and inflammatory markers, and the microorganisms include any one or more selected from the group consisting of bacteria, viruses, fungi and parasites.

7. The method according to claim 5 or 6; further comprising the step of subjecting the apparatus to sonication to form a sonication fluid, the sonication step serving to disintegrate a biofilm of microorganisms present in the absorbed and adsorbed biological material so as to form a sonication fluid containing microorganisms.

8. The method according to claim 7, wherein the sonication is performed at frequencies of 20 kilohertz.