Culture medium for screening and screening method

Abstract

Provided is a screening medium and a screening method, which can simply and quickly investigate the presence of Candida auris. A screening medium, the screening medium contains an enzyme substrate and is used for screening Candida auris according to the degradation ability of the enzyme substrate, wherein the enzyme substrate contains raffinose and xylose.

Description

Technical Field

[0001] The present invention relates to a screening medium and a screening method for identifying and screening Candida auris.

[0002] This application claims priority based on Japanese Patent Application No. 2020-17999 filed in Japan on February 5, 2020, and incorporates its content herein. Background Art

[0003] There are more than 400 known species of Candida as pathogens of candidiasis, and 20 species are clinically important. Since most of these are morphologically and biochemically similar, they are generally difficult to distinguish.

[0004] There have been studies on methods for identifying existing species of Candida from other species. For example, Patent Document 1 discloses a simple identification medium for Candida in a sub-low medium supplemented with a pigment, 2,3,5-triphenyltetrazolium chloride (TTC), and yeast extract. This simple identification medium for Candida is for Candida albicans and Candida glabrata, and uses the difference in the redox ability of these strains on the medium to distinguish the two Candida species by the color of the colonies.

[0005] Patent Document 2 discloses a method for detecting the presence of a specific microbial strain in a culture medium. In this method, as a substrate for an enzyme specific to the strain, at least one chromogen is added to the culture medium, and at least one compound selected from carbohydrates is added at a high concentration, and an induced color different from the basic color of the chromophore is obtained after the chromogen is hydrolyzed. This method is for enzymes produced by each of Candida albicans and Candida tropicalis. Two chromogens that are substrates for these enzymes are added to the culture medium, and a color different from the basic color of the chromophore is obtained after the chromogen is hydrolyzed to distinguish the two.

[0006] Prior Art Documents

[0007] Patent Documents

[0008] Patent Document 1: Japanese Unexamined Patent Application Publication No. 06-78793

[0009] Patent Document 2: Japanese Patent Application Laid-Open No. 09-500790 Summary of the Invention

[0010] Problems to be Solved by the Invention

[0011] Even among Candida species, Candida auris, discovered and named by the present inventors, is multi-drug resistant and has a high fatality rate, posing a global threat. Even among Candida species, there is a particular need for a simple and rapid method to investigate its presence in a specific environment (e.g., a certain enclosed space such as a hospital ward).

[0012] To identify Candida auris relative to other fungi such as other Candida species, it is possible to identify it by analyzing the genes of the fungus, for example. However, such analysis requires equipment and is neither simple nor time- and cost-effective.

[0013] In the detection techniques using the degradation ability of enzyme substrates described in Patent Document 2 and the like, detection can be carried out with relatively simple equipment, operation, and a short culture time. The above techniques and the detection methods applying these techniques can detect other Candida species such as Candida albicans and Candida tropicalis. However, in the above techniques, no method for differentiating Candida auris from other Candida species has been found, and this technique cannot detect it.

[0014] Therefore, no technique for simply and rapidly investigating the presence of Candida auris has been found yet.

[0015] The present invention has been completed in view of the above circumstances, and an object thereof is to provide a screening medium and a screening method using the medium, which can simply and rapidly investigate the presence of Candida auris.

[0016] Means for Solving the Problem

[0017] To solve the above problems, the present invention has the following aspects.

[0018] (1) A screening medium containing an enzyme substrate and used for screening Candida auris based on the degradation ability of the enzyme substrate, wherein the enzyme substrate contains raffinose and xylose.

[0019] (2) The screening medium according to any one of the above, wherein the Candida auris is an East Asian strain of Candida auris, and the enzyme substrate further contains N-acetylglucosamine.

[0020] (3) The screening medium according to any one of the above, wherein the Candida auris is an East Asian strain of Candida auris, and the enzyme substrate further contains potassium gluconate.

[0021] (4) The screening medium according to any one of the above, wherein the enzyme substrate further contains glycerol.

[0022] (5) The screening medium according to any one of the above, wherein the enzyme substrate further contains D-glucosamine hydrochloride.

[0023] (6) The screening culture medium according to any one of the above, wherein the enzyme substrate is labeled to show different colors when degraded.

[0024] (7) A screening method, which screens microorganisms according to the degradation ability of an enzyme substrate. When the enzyme substrate contains raffinose and the microorganism has a positive degradation ability for raffinose, and the enzyme substrate contains xylose and the microorganism has a negative degradation ability for xylose, the microorganism is determined to be Candida auris.

[0025] (8) The screening method according to any one of the above, wherein when the enzyme substrate further contains N-acetylglucosamine and the microorganism has a negative degradation ability for N-acetylglucosamine, the microorganism is determined to be an East Asian strain of Candida auris.

[0026] (9) The screening method according to any one of the above, wherein when the enzyme substrate further contains potassium gluconate and the microorganism has a negative degradation ability for potassium gluconate, the microorganism is determined to be an East Asian strain of Candida auris.

[0027] (10) The screening method according to any one of the above, wherein when the enzyme substrate further contains glycerol and the microorganism has a negative degradation ability for glycerol that is greater than 0% and 20% or less, the microorganism is determined to be an East Asian strain of Candida auris.

[0028] (11) The screening method according to any one of the above, wherein when the enzyme substrate further contains glycerol and the microorganism has a positive degradation ability for glycerol, the microorganism is determined to be a South American, African or South Asian strain of Candida auris.

[0029] (12) The screening method according to any one of the above, wherein when the enzyme substrate is D-glucosamine hydrochloride and the microorganism has a negative degradation ability for D-glucosamine hydrochloride, the microorganism is determined to be an East Asian strain of Candida auris.

[0030] (13) The screening method according to any one of the above, wherein when the enzyme substrate is D-glucosamine hydrochloride and the microorganism has a positive degradation ability for D-glucosamine hydrochloride that is 80% or more and less than 100%, the microorganism is determined to be a South American strain of Candida auris.

[0031] (14) The screening method according to any one of the above, wherein when the enzyme substrate is D-glucosamine hydrochloride and the microorganism has a positive degradation ability for D-glucosamine hydrochloride, the microorganism is determined to be an African or South Asian strain of Candida auris.

[0032] (15) The screening method according to any one of the above includes the following steps: inoculating a sample into a screening medium containing the enzyme substrate; culturing the microorganisms contained in the sample in the screening medium; and detecting the microorganisms in the screening medium.

[0033] (16) The screening method according to any one of the above, wherein a screening medium capable of detecting the degradation ability of the microorganisms to the enzyme substrate according to the color development of different colors for each enzyme substrate is used.

[0034] (17) The screening method according to any one of the above, wherein in the step of culturing the microorganisms, the culture is carried out at a temperature above 35°C.

[0035] Advantages of the Invention

[0036] Through the present invention, a screening medium and a screening method using the medium can be obtained, which can simply and quickly investigate the presence of Candida auris. Detailed Embodiments

[0037] Hereinafter, embodiments will be shown to illustrate the screening medium and the screening method provided by the present invention. However, the present invention is not limited to the following embodiments.

[0038] (Screening Medium)

[0039] (Medium Containing RAF and XYL)

[0040] The screening medium of the present embodiment contains an enzyme substrate, and this screening medium is used to screen Candida auris through the degradation ability of the enzyme substrate, and the enzyme substrate contains raffinose and xylose.

[0041] The so-called screening generally refers to the operation of screening microorganisms. Generally, it refers to the operation of screening a sample containing the target microorganisms to be screened for the presence or absence of a certain microorganism at the stage of whether there is such a possibility. Screening also refers to the stage of obtaining further information for distinguishing the possibility that a sample may contain a certain microorganism (for example, distinguishing the possibility from the results of multiple screenings).

[0042] The screening operation can be carried out once or multiple times, the same screening operation can be carried out multiple times, and this series of operations can also be collectively referred to as screening.

[0043] The screening medium of the present embodiment is used to screen Candida auris.

[0044] Among Candida auris, strains are classified into clades such as South America, Africa, East Asia (Japan and South Korea), South Asia (India), etc. according to their origin. As long as it is Candida auris, the screening medium of the present embodiment can screen any strain belonging to any clade.

[0045] Specifically, the screening medium of the present embodiment screens the presence, absence, or classification of certain bacteria (whether a certain microorganism is the certain bacteria) by whether a certain microorganism has an enzyme for degrading a specific compound as a substrate, that is, by whether it has the ability to degrade a specific enzyme substrate. When a microorganism uses an enzyme substrate as a nutrient, the degradation ability is also called assimilation. The enzyme substrates degraded by bacteria include various carbohydrates (sugars) used in the present embodiment, etc.

[0046] As such a screening medium, for example, a known enzyme substrate medium can be used. The enzyme substrate medium is a medium containing an enzyme substrate labeled with a chromogen (color-developing substance) that is specifically metabolized (degraded, assimilated) by the target microorganism (bacterial species). When the target bacterial species ingests the enzyme substrate and metabolizes it, the chromogen dissociates, and the condensed chromogen develops color, so that the bacterial species with the ability to degrade the enzyme substrate can be screened out.

[0047] As a chromogen for labeling the enzyme substrate, for example, a compound that releases two different chromophores capable of a coupling reaction by hydrolysis can be used. As such a compound, for example, an indole derivative can be used. When the medium contains multiple enzyme substrates, it is preferable to use chromogens that show different colors for each enzyme substrate, for example, chromogens of different compounds.

[0048] The screening medium of the present embodiment contains raffinose (RAF) and xylose (XYL) in the enzyme substrate.

[0049] Candida auris shows a positive degradation ability for raffinose and a negative degradation ability for xylose. Specifically, all 44 strains of Candida auris, including the above-mentioned various clades, show positive for raffinose (positive rate is 100%), and negative for xylose (positive rate is 0%). Therefore, when the microorganism cultured in the screening medium of the present embodiment shows a positive degradation ability for raffinose and a negative degradation ability for xylose, it is very likely that the microorganism is Candida auris. In addition, no combination of positive degradation ability for raffinose and negative degradation ability for xylose was found among other major pathogenic bacteria except Candida auris. Therefore, the medium of the present embodiment can be used to screen Candida auris.

[0050] When the screening medium is an enzyme substrate medium, it is preferable that the medium contains raffinose and xylose labeled with a chromogen, which show different colors during degradation respectively.

[0051] According to the above composition, among the microbial colonies cultured on a solid medium, colonies that exhibit the color during raffinose degradation but do not exhibit the color during xylose degradation can be screened out as Candida auris, while colonies that only exhibit the color during xylose degradation or exhibit the colors during both raffinose and xylose degradation are not Candida auris.

[0052] (Culture medium containing other substrates)

[0053] In addition to raffinose and xylose, the enzyme substrates contained in the screening culture medium of this embodiment may further contain other enzyme substrates. As the enzyme substrates, those for identifying existing bacterial species can be appropriately selected. As a preferred example, the screening culture medium may contain N-acetylglucosamine (NAG), potassium gluconate (GNT), glycerol (GLY), or D-glucosamine hydrochloride (GLN). As described below, by further containing these enzyme substrates in addition to raffinose and xylose, the screening culture medium can obtain information on which lineage the strain belongs to in addition to whether the microorganism is Candida auris.

[0054] When the screening culture medium is the above enzyme substrate culture medium and contains other enzyme substrates in addition to raffinose and xylose, it is preferable to further label the other enzyme substrates to develop a color different from those of raffinose and xylose. According to this composition, information on whether the cultured microorganism is Candida auris and which lineage the strain belongs to can be obtained based on the respective color developments indicating the degradation abilities of raffinose, xylose, or other enzyme substrates (such as N-acetylglucosamine).

[0055] (Other compositions)

[0056] When the screening culture medium of this embodiment is an enzyme substrate culture medium, other compositions can be used for existing culture media. For example, they can be appropriately selected from the components of enzyme substrate culture media with known compositions, such as chromogenic culture media. The enzyme substrate culture medium can contain nutrients such as peptone, yeast extract, sugar, minerals, and vitamins. As the nutrient, peptone is preferably used. The enzyme substrate culture medium can contain thickeners or pH regulators, etc. In addition, additives for improving the chromogenesis of enzyme substrates, such as redox reagents, etc., can also be contained.

[0057] The enzyme substrate culture medium can contain antibacterial agents to inhibit the growth of microorganisms other than the target microorganisms for screening. The antibacterial agents include aminoglycoside antibiotics, broad-spectrum antibiotics such as chloramphenicol or tetracycline, or cephalosporins or penicillins. For screening Candida auris, chloramphenicol is preferably used as the antibiotic.

[0058] The enzyme substrate medium can be in existing forms such as liquid, semi-fluid or solid as appropriate. However, when using, for example, a solid medium, especially a flat solid medium (plate-like), it is easier to culture and detect. To form a solid medium, traditional solidifying agents such as agar, carrageenan or terra japonica can be used, and agar is used in this embodiment.

[0059] Furthermore, except for the case where one medium contains all enzyme substrates, the screening medium containing multiple enzyme substrates can also be a combination of multiple media containing more than one of the multiple enzyme substrates. This embodiment also includes the following forms: for example, when a microorganism is isolated separately in advance and the sample only contains this microorganism, when obtaining information such as whether the microorganism is Candida auris and other lineages of this microorganism, the sample is cultured in different media containing different enzyme substrates respectively, and information on the degradation ability for each enzyme substrate is obtained.

[0060] (Screening method)

[0061] (Screening Candida auris through a medium containing RAF and XYL)

[0062] The screening method of this embodiment is a screening method for screening microorganisms according to the degradation ability of enzyme substrates. When the enzyme substrates include raffinose and the degradation ability of the microorganism for raffinose is positive, and the enzyme substrates include xylose and the degradation ability of the microorganism for xylose is negative, the microorganism is determined to be Candida auris. Specifically, the target microorganism is cultured using the above-mentioned screening medium for screening.

[0063] The screening method of this embodiment can be used to screen a sample containing multiple microorganisms to determine whether Candida auris is contained in the sample, or to screen a certain microorganism to determine whether it is likely to be Candida auris.

[0064] As a sample containing multiple microorganisms, a sample collected from a specific space where microorganisms may exist can be considered.

[0065] More specifically, the screening method of this embodiment includes the following steps: inoculating the sample into a screening medium containing enzyme substrates; culturing the microorganisms contained in the sample in the screening medium; and detecting the microorganisms in the screening medium.

[0066] For example, a method for screening whether Candida auris is contained in a sample containing multiple microorganisms using the above-mentioned enzyme substrate medium will be described.

[0067] First, the step of inoculating the sample into a screening medium containing enzyme substrates is carried out. The inoculation can be carried out as appropriate according to existing cell culture methods.

[0068] Next, perform the step of culturing the microorganisms contained in the sample. Specifically, by culturing the microorganisms in an enzyme substrate medium inoculated with the sample, the microorganisms form colonies on the enzyme substrate medium.

[0069] The conditions for culturing the enzyme substrate medium can be appropriately selected from the existing known microorganism culturing conditions. In the present embodiment, it is preferably cultured at 35°C or higher. By culturing at 35°C or higher, pathogenic bacteria that grow under conditions close to human body temperature can be cultured, and microorganisms that do not grow at lower temperatures can be removed. In addition, it is also preferably cultured at a temperature higher than 40°C and lower than 42°C. Since Candida auris can grow even at 41°C, culturing under this temperature condition can remove other microorganisms that grow up to 40°C.

[0070] The culturing time can be appropriately selected from the existing known microorganism culturing conditions. For example, culture for 24 hours or more, preferably 48 hours or more. By culturing for the above-mentioned time, colonies can be fully formed to the extent that color development can be confirmed.

[0071] Next, perform the step of detecting the microorganisms in the screening medium. In the present embodiment, by confirming the color development of the microbial colonies formed in the enzyme substrate medium, it is screened whether the microorganisms in the colonies are Candida auris. For the confirmation of color development, for each microbial colony, it is only necessary to visually observe whether the chromophore marked on the enzyme substrate is colored.

[0072] In the above enzyme substrate medium, a screening medium that can detect the degradation ability of microorganisms to enzyme substrates according to the color development of different colors for each enzyme substrate is used. That is, in the enzyme substrate medium of the present embodiment, raffinose and xylose of the enzyme substrate are labeled so that they show different colors when degraded. As described above, Candida auris shows the degradation ability to raffinose but does not show the degradation ability to xylose. Therefore, among the colonies of the microorganisms cultured in the medium, the colonies of the microorganisms that show the color developed when raffinose is degraded but do not show the color developed when xylose is degraded can be judged as Candida auris. For a sample containing multiple microorganisms, when inoculated onto the enzyme substrate medium, if the cultured colonies contain the colored colonies, it can be judged that the sample contains Candida auris.

[0073] (Screening of bacterial lineages using a medium containing other substrates)

[0074] When the screening medium of the present embodiment further contains N-acetylglucosamine (NAG), strains of the East Asian lineage in Candida auris show negative for N-acetylglucosamine, while strains of the South American, African, and South Asian lineages show positive. Therefore, using this medium, strains of the East Asian lineage of Candida auris can be screened.

[0075] It is known that among the lineages of Candida auris, compared with the East Asian lineage, the pathogenicity of other lineages is higher. Among the East Asian lineages, it is basically limited to local infections of the inner ear and outer ear, so it is considered that fatal infections may not necessarily occur.

[0076] That is to say, by screening whether a microorganism is Candida auris and whether it belongs to the East Asian lineage, information about the risk of the microorganism or the sample containing the microorganism and the environment where the sample is collected can be obtained.

[0077] In addition, when potassium gluconate (GNT) is included in the screening medium of the present embodiment, strains of the East Asian lineage in Candida auris show negative for N-acetylglucosamine, while strains of the South American, African, and South Asian lineages show positive. Therefore, information for screening strains of the East Asian lineage of Candida auris can be obtained by using this medium.

[0078] In addition, when glycerol (GLY) is included in the screening medium of the present embodiment, among Candida auris, only a part (about greater than 0% and less than 20%) of the strains of the East Asian lineage show positive for glycerol, while strains of the South American, African, and South Asian lineages show positive. Therefore, information for screening strains of the East Asian lineage of Candida auris from other strains can be obtained by using this medium.

[0079] In addition, when D-glucosamine hydrochloride (GLN) is included in the screening medium of the present embodiment, strains of the East Asian lineage in Candida auris show negative for D-glucosamine hydrochloride, strains of the African and South Asian lineages show positive, and most (about greater than 80% and less than 100%) of the strains of the South American lineage show positive. Therefore, information for screening strains of the East Asian lineage of Candida auris from other strains can be obtained by using this medium.

[0080] When the screening medium is the above-mentioned enzyme substrate medium and contains other enzyme substrates different from raffinose and xylose, and further the other enzyme substrates are labeled to have different colors from raffinose and xylose in terms of color development, then whether the cultured microorganism is Candida auris and whether it is of the East Asian lineage can be screened according to the respective color developments indicating the degradation capabilities of raffinose, xylose, and other enzyme substrates (such as N-acetylglucosamine).

[0081] This screening based on color development can also appropriately combine two or more substrates and their respective different color developments. For example, when the screening object shows positive for two or more substrates, two or more color developments will be shown, and the colony of the microorganism will show the color of their mixed colors. Therefore, information about which substrate the reaction occurs to, that is, which lineage of strains is included in Candida auris, can also be obtained according to the color and shade of the colony.

[0082] (Effect of this embodiment)

[0083] The screening medium and screening method of this embodiment can simply and quickly screen for the presence of Candida auris. Specifically, for a sample containing multiple microorganisms, such as a sample collected from a specific space, only the simple operation of inoculating the sample on a plate solid medium and culturing it, and the presence of Candida auris can be screened within a short time of about 24 - 48 hours. As long as there is equipment capable of culturing the plate solid medium for inoculation and culturing, and for microorganism screening, only visual inspection of the color development is required without special equipment and instruments. Compared with gene analysis, etc., the screening cost of the plate solid medium is very low.

[0084] (Application examples of this embodiment)

[0085] As a sample to be screened in this embodiment, for example, it can be a sample collected from a specific space indoors or outdoors. As specific spaces, all places where Candida auris should be detected can be cited, for example, each room in a hospital, especially an operating room or a ward, etc. In addition, it can also be used in various institutions, welfare institutions with elderly or patient personnel, etc. If detection is carried out at an airport, customs, etc., it can be used for so-called entry-exit quarantine measures.

[0086] The screening medium and method of this embodiment can be used for the operation of combining multiple screenings to obtain information on the presence or absence of Candida auris or any lineage of bacteria.

[0087] In addition, the screening medium and method of this embodiment can be used in combination with other means. For example, the screening medium and method of this embodiment can be used as a preliminary screening to narrow down the objects to be subjected to more detailed gene analysis. The screening method of this embodiment can be carried out simply and quickly, so it is particularly effective when the number of samples (specific spaces where their presence is investigated) and lineages to be screened are relatively large.

[0088] (Other embodiments)

[0089] The screening method of this embodiment can also be used to screen whether a bacterium is Candida auris for a single microorganism. In this case, an enzyme substrate medium containing the above-mentioned raffinose and xylose, or containing other enzyme substrates can also be used for screening. In addition, this embodiment also includes a form of culturing in different media containing different enzyme substrates to obtain information on the degradation ability for each enzyme substrate.

[0090] For the enzyme substrate medium, although plate-shaped media are more convenient for directly culturing microorganisms, other forms are also possible. For example, the medium can also be formed into a thin film. Since it is not difficult to simply place the thin film medium in various places, directly culture it, and screen it, it can be placed in the specific space where Candida auris should be detected as described above.

[0091] Examples

[0092] Examples are shown below. It should be noted that the present invention is not limited to the following examples.

[0093] (Verification of Candida auris-specific enzyme substrates)

[0094] For various strains including Candida auris, the degradation ability of each enzyme substrate was studied. As Candida auris, 44 strains shown in Table 1 were used (as lineages, 10 strains belong to the species in South America, 10 strains in Africa, 10 strains in East Asia, and 14 strains in South Asia). Other strains were selected from representative pathogenic yeast strains in Japan. The strains used are shown as strains other than Candida auris in Table 2.

[0095] Among the enzyme substrates, for various enzyme substrates of raffinose (RAF), xylose (XYL), N-acetylglucosamine (NAG), potassium gluconate (GNT), glycerol (GLY), and D-glucosamine hydrochloride (GLN), the plate of the culture identification · fungal kit ID32C API (Sysmex biomerieux Co., Ltd.) was used as a kit capable of identifying the degradation ability as a positive rate.

[0096] The bacterial suspensions of each strain in Tables 1 and 2 were adjusted according to the protocol with a suspension medium (liquid medium), and extracted into the positive rate detection cups of each enzyme substrate on the plate of ID32C API, and cultured for 48 hours. After culturing, by visual judgment, the transparent wells identical to the control were judged as negative (-), and the wells less transparent than the control were judged as positive (+), and the positive data were analyzed using the database software 4.0 attached to ID32C API.

[0097] Table 1

[0098]

[0099] Table 2

[0100]

[0101] As shown in Table 1, all 44 strains of the four lineages of Candida auris were positive for RAF degradation ability and negative for XYL degradation ability.

[0102] In Table 2, Candida auris (the bottom row of the table) showed that the RAF degradation ability of all 44 strains was positive (100%), and the XYL degradation ability was negative (0%). On the other hand, as shown in the other rows of Table 2, among the pathogenic strains other than Candida auris, no combination was found with 100% positive RAF degradation ability and negative XYL degradation ability (positive was 0%).

[0103] That is to say, among the main pathogenic strains, only Candida auris had 100% positive RAF degradation ability and 100% negative XYL degradation ability. This indicates that the presence or absence of Candida auris can be screened by detecting the RAF degradation ability and the XYL degradation ability.

[0104] Among the 44 strains of Candida auris, as shown in Table 1, in addition to the results of positive for RAF and negative for XYL, NAG was 100% negative in the East Asian strains.

[0105] That is to say, this indicates that in addition to RAF and XYL, the East Asian strains and other strains of this Candida auris can also be screened by detecting the degradation ability of NAG.

[0106] In addition, as shown in Table 1, the GNT of the East Asian strains was 0% positive, while that of the strains outside East Asia was 100% positive.

[0107] The East Asian lineage showed 10% positive for GLY (that is, only 1 out of 10 strains in East Asia showed positive). It can be considered that among the strains belonging to the East Asian lineage, there are strains that show positive for GLY in the range of approximately 0 - 20%. On the other hand, the strains outside East Asia were 100% positive.

[0108] GLN was 0% positive in the East Asian lineage. In contrast, it was 100% positive in Africa and South Asia, and 90% positive in South America. It can be considered that among the strains belonging to the South Asian lineage, there are strains that show positive for GLY in the range of approximately 80 - 100%.

[0109] That is to say, it can be considered that strains with a low GLY positive rate and GLN-negative strains can be distinguished as strains of the East Asian lineage from other strains, and these combinations can be used for the screening and judgment of each strain.

[0110] Industrial Applicability

[0111] Through the present invention, a screening medium and a screening method using the medium can be obtained, which can simply and quickly investigate the presence of Candida auris.

Claims

1. A screening method, which screens microorganisms as Candida according to the degradation ability of enzyme substrates, and determines that the microorganism is Candida auris, when the enzyme substrate contains raffinose, the degradation ability of the microorganism to raffinose is positive, the enzyme substrate contains xylose, and the degradation ability of the Candida microorganism to xylose is negative, it is determined that the microorganism is Candida auris.

2. The screening method according to claim 1, wherein, when the enzyme substrate further contains N-acetylglucosamine and the degradation ability of the microorganism to N-acetylglucosamine is negative, it is determined that the microorganism is an East Asian strain of Candida auris.

3. The screening method according to claim 1, wherein, when the enzyme substrate further contains potassium gluconate and the degradation ability of the microorganism to potassium gluconate is negative, it is determined that the microorganism is an East Asian strain of Candida auris.

4. The screening method according to claim 1, wherein, when the enzyme substrate further contains glycerol and the degradation ability of the microorganism to glycerol is negative, it is determined that the microorganism is an East Asian strain of Candida auris.

5. The screening method according to claim 1, wherein, when the enzyme substrate further contains glycerol and the degradation ability of the microorganism to glycerol is positive, it is determined that the microorganism is a South American, African or South Asian strain of Candida auris.

6. The screening method according to claim 1, wherein, when the enzyme substrate is D-glucosamine hydrochloride and the degradation ability of the microorganism to D-glucosamine hydrochloride is negative, it is determined that the microorganism is an East Asian strain of Candida auris.

7. The screening method according to claim 1, wherein, when the enzyme substrate is D-glucosamine hydrochloride and the degradation ability of the microorganism to D-glucosamine hydrochloride is positive, it is determined that the microorganism is a South American, African or South Asian strain of Candida auris.

8. The screening method according to any one of claims 1-7, which comprises the following steps: inoculating the sample into a screening medium containing the enzyme substrate; culturing the microorganisms contained in the sample in the screening medium; and detecting the microorganisms in the screening medium.

9. The screening method according to claim 8, wherein, a screening medium capable of detecting the presence of the degradation ability by color development of different colors for each enzyme substrate according to the degradation ability of the microorganism to the enzyme substrate is used.

10. The screening method according to claim 8, wherein, in the step of culturing the microorganisms, the culture is carried out at a temperature above 35°C.

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