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  • C12Q1/527—Measuring or testing processes involving enzymes, nucleic acids or microorganisms; Compositions therefor; Processes of preparing such compositions involving lyase

Definitions

• the field of the invention is that of microbiological analysis by means of biochemistry, and in particular the detection and identification of microorganisms, for instance of bacteria or yeasts.
• Bacterial resistance to antibiotics is a major public health problem.
• the resistance of infectious microorganisms to a treatment has developed at the same time as anti-infectious molecules and today represents a major obstacle in therapeutics. This resistance is responsible for many problems, including difficulties in detection in the laboratory, limited treatment options and a deleterious impact on clinical outcome.
• Enzymatic inactivation is the most common mechanism of acquired resistance in terms of number of species and of antibiotics involved.
• chromosomal class C cephalosporinases today constitute one of the predominant resistance mechanisms of gram-negative bacteria, the bacteria expressing such enzymes being resistant to cephalosporins.
• ⁇ -lactamases are enzymes expressed by certain bacteria, capable of hydrolyzing the C—N bond of the ⁇ -lactame ring, the basic structure of antibiotics of the ⁇ -lactamine family, so as to give a microbiologically inactive product.
• ⁇ -lactamase inhibitors such as clavulanic acid (CA), tazobactam and sulbactam
• CA clavulanic acid
• tazobactam tazobactam
• sulbactam sulbactam
• Gram-negative bacteria which produce high-level chromosome class C cephalosporinases reference is made to HL Case bacteria
• gram-negative bacteria which produce extended-spectrum ⁇ -lactamase reference is then made to ESBL bacteria
• HL Case and ESBL bacteria are resistant to treatments based on 1st- and 2nd-generation penicillins and cephalosporines, but also on 3rd-generation cephalosporines (C3G) (cefotaxim CTX, ceftazidime CAZ, cefpodoxime CPD, ceftriaxone CRO) and monobactams (aztreonam ATM).
• 7 ⁇ -methoxycephalosporins (cephamycins: cefoxitin, cefotetan) and carbapenems (imipenem, meropenem, ertapenem) generally conserve their activity.
• ESBLs are inhibited by ⁇ -lactamase inhibitors (BLIs), which makes it possible to differentiate them from other cephalosporinases.
• Escherichia coli bacterium can thus be HL Case and ESBL.
• ESBL-positive enterobacteria have a tendency to disseminate the resistance by clonal transmission of strains or conjugative plasma transfer, they represent a problem in terms of controlling infections.
• Escherichia coli and Klebsiella pneumoniae remain the most common ESBL-producing species.
• ESBLs have greatly broadened their panel of host species.
• many species of enterobacteria and of nonfermenting gram-negative bacilli such as Pseudomonas aeruginosa ) have also been reported to ESBL producers.
• Staphylococcus aureus bacteria which are also pathogenic bacteria that develop many mechanisms of resistance, such as resistance to methicillin, penicillin, tetracycline, erythromycin, or vancomycin.
• Enterococcus faecium is another multiresistant bacterium found in the hospital environment, which can be resistant to penicillin, vancomycin and linezolide.
• Mycobacterium tuberculosis is commonly resistant to isoniazid and to rifampicin.
• Other pathogens offer certain resistances, such as Salmonella, Campylobacter and Streptococcus.
• the search for microorganisms resistant to a treatment is carried out according to the following steps:
• This succession of steps involves a considerable amount of time between taking the sample that may contain microorganisms and prescribing a treatment that is appropriate for the patient. Furthermore, the user must generally perform steps for transferring microorganims from a first medium to a second medium manually, which can induce problems, in particular, of contamination, but also risks to the handler's health.
• ESBLs broad-spectrum beta-lactamases
• a diffusion technique as described in the publication by Jacoby & Han (J Clin Microbiol. 34(4): 908-11, 1996), which does not however give any information regarding the identification of the strains tested: it is possible to determine whether or not the bacterium is a ESBL-producing bacterium, but it is not possible to distinguish whether such a bacterium is an Escherichia coli or a Klebsiella pneumoniae.
• Metabolic substrates are also used for detecting the presence of ESBLs or HL cases.
• AES laboratories proposes a medium in a biplate combining a Drigalski medium with cefotaxim and a MacConkey medium with ceftazidime.
• the Drigalski and MacConkey media make it possible to reveal lactose acidification, a metabolism which is present in a very large number of enterobacterial species.
• such a medium only makes it possible to distinguish resistant bacteria from non-resistant bacteria, and does not make it possible to distinguish bacteria expressing a ESBL from those expressing an HL Case. Neither does this medium make it possible to identify specific bacterial species, nor does it make it possible, for example, to discriminate between E. coli bacteria and K. pneumoniae bacteria.
• the present invention therefore proposes to improve the prior art by providing a novel diagnostic tool which allows a gain in time, in reliability and in relevance with respect to the therapy implemented.
• Our invention makes it possible, in a single step, to identify the species of microorganisms present in a sample, and to determine their mechanism of resistance in order to propose a treatment appropriate to each patient.
• This invention is particularly suitable for discriminating various species of microorganisms, which have various mechanisms of resistance to various treatments, but all of which may be present in the same sample.
• culture medium is intended to mean a medium comprising all the elements required for the survival and/or the growth of microorganisms.
• the culture medium according to the invention may contain any possible additives, for instance: peptones, one or more growth factors, carbohydrates, one or more selective agents, buffers, one or more gelling agents, etc.
• This culture medium may be in liquid form or in gel form which is ready to use, i.e. ready for seeding in a tube or flask or on a Petri plate.
• microorganism covers gram-positive or gram-negative bacteria, yeasts and, more generally, organisms that are generally unicellular, invisible to the naked eye, which can be multiplied and handled in the laboratory.
• bacteria of the following genres Pseudomonas, Escherichia, Salmonella, Shigella, Enterobacter, Klebsiella, Serratia, Proteus, Campylobacter, Haemophilus, Morganella, Vibrio, Yersinia, Acinetobacter, Branhamella, Neisseria, Burkholderia, Citrobacter, Hafnia, Edwardsiella, Aeromonas, Moraxella, Pasteurella, Providencia, and Legionella.
• bacteria By way of gram-positive bacteria, mention may be made of bacteria of the following genre: Enterococcus, Streptococcus, Staphylococcus, Bacillus, Listeria, Clostridium, Gardnerella, Kocuria, Lactococcus, Leuconostoc, Micrococcus, Mycobacteria and Corynebacteria.
• yeasts By way of yeasts, mention may be made of yeasts of the following genre: Candida, Cryptococcus, Saccharomyces and Trichosporon.
• biological sample is intended to mean a clinical sample, derived from a specimen of biological fluid, or a food sample, derived from any type of food.
• This sample may thus be liquid or solid and mention may be made, in the nonlimiting manner, of a clinical blood, plasma, urine or faeces sample, nose, throat, skin, wound or cephalospinal fluid specimens, a food sample from water, from drinks such as milk or a fruit juice; from yoghurt, from meat, from eggs, from vegetables, from mayonnaise, from cheese; from fish, etc., a food sample derived from a feed intended for animals, such as, in particular, a sample derived from animal meals.
• the term “mechanism of resistance” is intended to mean any type of device which allows a microorganism to render a treatment partially or completely ineffective on said microorganism, guaranteeing its survival.
• the mechanisms of resistance are generally divided up into three categories: deficient penetration of the antibiotic into the bacterium, inactivation or excretion of the antibiotic by means of bacterial enzymatic systems, and lack of affinity between the bacterial target and the antibiotic.
• treatment is intended to mean a treatment capable of preventing or reducing the growth of microorganisms derived from a patient.
• This treatment may comprise in particular antimicrobial compounds, such as antibiotics, for instance penicillins, conventional cephalosporins, broad-spectrum cephalosporins, monobactams, glycopeptides or aminosides, or such as antifungals or resistance-inhibiting compounds.
• antibiotics for instance penicillins, conventional cephalosporins, broad-spectrum cephalosporins, monobactams, glycopeptides or aminosides, or such as antifungals or resistance-inhibiting compounds.
• this treatment can also comprise the isolation of the patient, thereby preventing propagation of the microorganism among other patients.
• substrate which allows the detection of an enzymatic or metabolic activity is intended to mean any molecule capable of directing or indirectly generating a detectable signal due to an enzymatic or metabolic activity of the microorganism.
• enzyme substrate is intended to mean any substrate that can be hydrolyzed by an enzyme into a product that allows the direct or indirect detection of a microorganism.
• This substrate comprises in particular a first part that is specific for the enzymatic activity to be revealed and a second part that acts as a label, hereinafter referred to as labeling part.
• labeling part may be chromogenic, fluorogenic, luminescent, etc.
• chromogenic substrate suitable for solid supports filter, agar, electrophoresis gel
• substrates based on indoxyl and its derivatives and substrates based on hydroxyquinoline or escultin and their derivatives, which allow the detection of osidase and esterase activities.
• substrates based on naphtol and naphtylamine and their derivatives which make it possible to detect osidase and esterase activities via naphtol, and peptidase activities via naphtylamine.
• This substrate may allow, in particular, but in a nonlimiting manner, the detection of an enzymatic activity such as the activity of an osidase, peptidase, esterase, etc.
• the enzymatic substrate can also be a natural substrate of which the product of hydrolysis is detected directly or indirectly.
• tryptophan for detecting tryptophanase or desaminase activity
• a cyclic amino acid for detecting desaminase activity
• phosphatidyl inositol for detecting phospholipase activity
• the substrate is then a metabolic substrate, such as a source of carbon or of nitrogen, coupled to an indicator that produces a coloration in the presence of one of the metabolic products.
• said first and/or second enzymatic or metabolic activity is an enzymatic activity preferably chosen from the enzymatic activities: beta-glucosidase, desaminase, beta-glucuronidase, beta-galactosidase, alpha-glucosidase, alpha-galactosidase, hexosaminidase, N-acetyl-hexosaminidase, phosphatase, esterase, and aminopeptidase.
• beta-glucuronidase or ⁇ -galactosidase or tryptophanase or desaminase activity For example, for detecting E. coli, use is preferably made of beta-glucuronidase or ⁇ -galactosidase or tryptophanase or desaminase activity; for detecting Proteus, use is preferably made of desaminase activity; for detecting enterococci, use is preferably made of beta-glucosidase activity.
• hexosaminidase is preferred, for Listeria monocytogenes, phospholipase is preferred, for salmonellae, esterase is preferred, for Pseudomonas aeruginosa, esterase or ⁇ -alanine aminopeptidase is preferred, for Staphylococcus aureus phosphatase or alpha-glucosidase is preferred.
• the expression “marker for differentiating” two groups of microorganisms is intended to mean a compound which does not have the same properties on a first and on a second group.
• This compound may thus be:
• beta-glucuronidase In the case of the use of a specific substrate, use is preferably made of beta-glucuronidase, beta-galactosidase, tryptophanase or desaminase activity for detecting E. coli, use is preferably made of desaminase activity for detecting Proteus, use is preferably made of beta-glucosidase activity for detecting enterococci.
• hexosaminidase is preferred, for Listeria monocytogenes, phospholipase is preferred, for salmonellae, esterase is preferred, for Pseudomonas aeruginosa, esterase or ⁇ -alanine aminopeptidase is preferred, for Staphylococcus aureus, phosphatase or alpha-glucosidase is preferred.
• taxon is intended to mean a group of microorganisms having a taxonomic unit.
• a taxon may be a family, a genus, a set of genre, a species, a set of species or a subspecies.
• enterobacteria Klebsiella, Escherichia, Enterobacter, Citrobacter, Serratia, KESC ( Klebsiella, Enterobacter, Serratia, Citrobacter ), Proteeae, Proteus, Morganella, Pseudomonas, Staphylococcus, Streptococcus, Enterococcus, Candida, Escherichia coli, Escherichia coli 0157:H7, Klebsiella pneumoniae, Citrobacter freundii, Enterococcus faecalis, Enterococcus faecium, Staphylococcus aureus, coagulase-negative staphylocoque, Candida albicans, Candida glabrata, Candida krusei, Candida lusitaniae.
• antifungal is intended to mean any compound capable of preventing or slowing down the growth of a microorganism. This compound may be an antibiotic or an antifungal.
• antibiotic is intended to mean any compound capable of preventing or slowing down the growth of a bacterium.
• antibiotics cefotaxime, ceftazidime, ceftriaxone, cefpodoxime, aztreonam, vancomycin, tobramycin and ciprofloxacin are examples of the antibiotics cefotaxime, ceftazidime, ceftriaxone, cefpodoxime, aztreonam, vancomycin, tobramycin and ciprofloxacin.
• antifungal is intended to mean any compound capable of preventing or slowing down the growth of a yeast or of a mould.
• amphotericin B fluconazole, itraconazole, voriconazole and cycloheximide.
• the medium comprises a combination of at least two antibiotics.
• the combination of at least two antibiotics comprises cefotaxime and ceftazidime.
• the medium may also comprise a dye.
• a dye By way of indication of a dye, mention may be made of Evans blue, neutral red, sheep blood, horse blood, and opacifier such as titanium oxide, nitroaniline, malachite green, brilliant green, etc.
• All the media may also comprise, in order to increase their sensitivity:
• the invention relates to the use of a combination of two culture media for distinguishing at least three groups of microorganisms in a biological sample, comprising:
• said combination of two culture media comprising:
• the medium comprises at least two markers for differentiating the first group of microorganisms and the second group of microorganisms, at least one of which is an inhibitor of said first or said second mechanism of resistance.
• the medium may also comprise at least two markers for differentiating the first group of microorganisms and the second group of microorganisms, which are each an inhibitor of said first or said second mechanism of resistance.
• This first embodiment of the invention makes it possible to distinguish, in the same sample, a first and a second group comprising various species or various taxons of microorganisms, each of the two groups being resistant to a different treatment.
• This embodiment of the invention thus makes it possible, for example, to distinguish, in the same sample, a first group comprising E. coli ESBL bacteria and a second group comprising KESC HL Case bacteria.
• the combination of two media may be the following:
• a first medium may comprise:
• the second medium comprises:
• each medium so as to systematically obtain a combination according to the invention.
• the antimicrobial that is active on said third group is present in the two media.
• Those skilled in the art may in particular use a biplate, for readily comparing the two media on which the same biological sample has been deposited.
• the invention also relates to a biplate comprising a combination of two culture media, said combination comprising:
• This first embodiment of the invention is not limited to distinguishing between 3 groups of microorganisms, but may make it possible to distinguish between 4, 5 or even more groups of microorganisms. It is then necessary to add additional identification markers to the medium or media, in order to discriminate between the various groups.
• the invention also relates to a biplate comprising a combination of two culture media, said combination comprising:
• the invention also relates to the use of a culture medium for distinguishing at least 3 groups of microorganisms in a biological sample, comprising:
• said culture medium comprising:
• This second embodiment of the invention makes it possible to distinguish, in the same sample, a first and a second group comprising various species or various taxons of microorganisms, but each of the two groups being resistant to the same treatment.
• This embodiment of the invention thus makes it possible, for example, to distinguish, in the same sample, a first group comprising E. coli ESBL bacteria and a second group comprising KESC ESBL bacteria.
• the invention relates to a culture medium comprising:
• this medium is preferably used for distinguishing:
• the invention also relates to a culture medium comprising:
• this medium is preferably used to distinguish:
• the invention also relates to a culture medium comprising:
• this medium is preferably used to distinguish:
• the invention also relates to a culture medium comprising:
• this medium is preferably used to distinguish:
• the invention also relates to a culture medium comprising:
• this medium is preferably used to distinguish:
• the invention also relates to a culture medium comprising:
• this medium is preferably used to distinguish:
• the invention also relates to a culture medium comprising:
• this medium is preferably used to distinguish:
• the invention also relates to a culture medium comprising:
• This medium is preferably used to distinguish:
• the invention also relates to a culture medium comprising:
• This medium is preferably used to distinguish:
• the invention also relates to a culture medium comprising:
• this medium is preferably used to distinguish:
• the first substrate is preferably methyl- ⁇ -glucoside
• the second substrate is preferably 5-bromo-4-chloro-3-indolyl- ⁇ -D-glucoside or 6-chloro-3-indolyl- ⁇ -D-glucoside
• the antimicrobial is preferably vancomycin.
• This medium is also preferably used to distinguish:
• the first substrate is preferably 5-bromo-4-chloro-3-indolyl-N-methyl- ⁇ -D-glucoside or 5-bromo-4-chloro-3-indolyl- ⁇ -D-glucoside
• the second substrate is preferably 6-chloro-3-indolyl- ⁇ -D-glucoside or alizarine- ⁇ -D-galactoside or 5 bromo-6-chloro-3-indolyl- ⁇ -D-glucoside or 5-bromo-6-chloro-3-indolyl- ⁇ -D-galactoside or 6-chloro-3-indolyl- ⁇ -D-galactoside
• the antimicrobial is preferably vancomycin.
• This medium is also preferably used to distinguish:
• the first substrate is preferably 5-bromo-4-chloro-3-indolyl-N-methyl- ⁇ -D-glucoside or 5-bromo-4-chloro-3-indolyl- ⁇ -D-glucoside
• the second substrate is preferably 6-chloro-3-indolyl- ⁇ -D-glucoside or 5-bromo-6-chloro-3-indolyl- ⁇ -D-glucoside
• the antimicrobial is preferably vancomycin.
• vancomycin concentration preferably to between 0.5 and 12 mg/l.
• the invention also relates to a culture medium comprising:
• This medium is also preferably used to detect ESBL bacteria.
• the second embodiment of the invention is not limited to distinguishing 3 groups of microorganisms, but can make it possible to distinguish 4, 5 or even more groups of microorganisms. It is then necessary to add, to the medium, markers for identification between the various groups.
• the invention also relates to a culture medium comprising:
• This medium may also comprise a fifth antibiotic, which is cefsulodine, at a concentration of between 0.5 and 64 mg/l, preferably between 1 and 16 mg/l.
• a fifth antibiotic which is cefsulodine
• This medium is preferably used to distinguish:
• the invention also relates to a culture medium comprising:
• this medium is preferably used to distinguish:
• This medium is also preferably used to distinguish:
• the invention also relates to the use of a combination of two culture media for distinguishing at least 3 groups of microorganisms in a biological sample, comprising:
• said combination of two culture media comprising:
• This third embodiment of the invention makes it possible to distinguish, in the same sample, a first and a second group comprising the same species of microorganisms or the same taxon, each of the two groups being resistant to different treatments.
• This embodiment of the embodiment thus makes it possible, for example, to distinguish, in the same sample, a first group comprising E. coli ESBL bacteria, and a second group comprising E. coli HL Case bacteria.
• the combination of two media may be the following:
• a first medium may comprise:
• an antimicrobial preferably an antibiotic, preferably cefpodoxime
• the second medium comprises:
• each medium in such a way as to systematically obtain a combination according to the invention.
• the antimicrobial that is active on said third group is present in the two media.
• Those skilled in the art may in particular use a biplate, which makes it possible to readily compare the two media on which the same biological sample would have been deposited.
• the invention also relates to a biplate comprising a combination of two culture media, said combination comprising:
• This third embodiment of the invention is not limited to distinguishing 3 groups of microorganisms, but may make it possible to distinguish 4, 5 or even more groups of microorganisms. It is then necessary to add additional identification markers to the medium, in order to discriminate the various groups.
• the invention relates to a biplate comprising a combination of two culture media, said combination comprising:
• the example below is based on the phenotypic detection of ESBLs using the reduction of susceptibility of these strains to antibiotics and their sensitivity to combinations with ⁇ -lactamases inhibitors.
• a biplate of CPS ID 3 base chromogenic medium for detecting microorganisms in urine, and sold by bioMerieux under the reference 43541 with one half-agar containing an antibiotic and one half-agar containing an antibiotic/ ⁇ -lactamases inhibitor combination was used.
• ESBL-positive strains high level cephalosporinase-producing strains (HL Case) and wild-type strains are compared in the trials.
• strains of gram-positive cocci Staphylococcus aureus, Staphylococcus saprophyticus, Staphylococcus epidermidis, Enterococcus faecalis, Enterococcus faecium, Streptococcus agalactiae
• gram-positive bacilli Lactobacillus spp
• yeasts Candida albicans, Candida glabrata, Candida tropicalis, Candida krusei, Candida dubliniensis, Saccharomyces cerevisiae, Geotrichum capitatum .
• the medium used was a CPS ID3 medium (reference 43541) also comprising at least one antibiotic and at least one resistance mechanism inhibitor.
• composition of the media tested was the following:
• Osmosed water is added and the whole is homogenized and melted in a waterbath at 100° C.
• the base medium is dispensed into flasks, the number of which corresponds to the total number of media to be tested during the process.
• the flasks are then autoclaved for 15 min at 121° C.
• the media are brought back to and kept molten at 55 ⁇ 3° C. in a waterbath, in order to sterilely add the thermolabile additives (sterilized beforehand by filtration through 0.22 ⁇ m).
• the media are then poured into biplates 90 mm in diameter (i.e. approximately 9.5 ml/half-plate), and left on a flat surface so that they can set.
• the surface of the agars is then dried under a laminar flow hood for 30 min.
• An inoculum of 0.5 McF is prepared, in physiological saline, from 24-hour precultures at 36° C. ⁇ 2° C. in an aerobic atmosphere on TSA medium, and then 1 ⁇ l of this suspension is transferred into 5 ml of physiological saline.
• a range of inocula made it possible to determine that the optimal amount of bacteria to be inoculated was from 10 3 to 10 4 CFU/ml.
• the inoculation is carried out directly on the two half-agars using a sterile swab. The cultures are then incubated at 37° C. in an aerobic atmosphere.
• Reading of media the readings are carried out at 18 hours ( ⁇ 30 min), 24 h ( ⁇ 1 h) and 48 h ( ⁇ 4 h). The density and the size of the colonies, and the appearance, the color and the coloration intensities of the mass and of the isolated colonies were observed, according to the following reading scales 1 to 3: 0: no growth; 0.1: trace of growth; 0.25: colonies of diameter ⁇ 0.5 mm; 0.5: colonies of 0.5 mm in diameter; 0.75: 0.5 mm ⁇ diameter ⁇ 1 mm; 1: colonies of 1 mm in diameter; 1.25: 1 mm ⁇ diameter ⁇ 1.5 mm; 1.5: colonies 1.5 mm in diameter; 2: colonies 2 mm in diameter; 3: colonies of diameter>2 mm.
• the low value corresponds to the minimum concentration of the antibiotic required to inhibit the wild-type strains of the enterobacteria tested.
• the high value corresponds to the maximum concentration of the antibiotic that can be used without affecting the growth of the ESBL-positive strains tested.
• ceftazidime is the only antibiotic tested and used in the detection of ESBLs which showed an activity on the wild-type strains of P. aeruginosa. A range was prepared in order to define the minimum concentration for complete inhibition of these strains, and the limiting value is 1.5 mg/l.
• ⁇ -lactamases inhibitors i.e. clavulanic acid, tazobactam and sulbactam.
• a range was prepared for each one, in the presence of cefotaxime, in order to determine the optimum concentration for inhibiting the ESBL-positive strains without impairing the growth of the HL Case strains.
• Clavulanic acid appeared to be the most effective BLI in the presence of cefotaxime. 25 Tazobactam and sulbactam required concentrations of greater than 2 mg/l in order to inhibit the ESBL-positive strains, whereas clavulanic acid was more active at much lower concentrations, over a broad operating range (from 0.1 to 8 mg/l when it is used in combination with cefotaxime).
• ⁇ -lactamase inhibitors had no effect on the expression of the bacterial enzymatic activities on the chromogenic medium.
• the groups of microorganisms were separated and identified both on control CPS ID 3 medium and on the media comprising ⁇ -lactamase inhibitors.
• the wild-type strains including those of pyocyanic bacillus
• the ESBL-positive strains of the enterobacteria tested by the addition of the BIL are included in the wild-type strains (including those of pyocyanic bacillus), and the ESBL-positive strains of the enterobacteria tested by the addition of the BIL.
• a medium according to the invention was also employed for use in a biplate, one of the sides containing an antibiotic, and the second containing another antibiotic or a combination of antibiotics. Given that the same CPS ID 3 medium base is used on either side, these two sides were differentiated by the presence of a dye.
• the dye tested gives the medium a green color.
• the coloration has made it possible to readily differentiate the 2 sides of the biplate without affecting the fertility of the medium, or impairing the reading of the enzymatic activities of the colonies.
• the values selected were the following:
• ESBLs are a mechanism of resistance to ⁇ -lactamines that is found only in gram-negative bacilli; it is therefore advisable to inhibit the gram-positive bacteria via the medium.
• a concentration between 2 and 32 mg/l, and in particular 2 to 5 mg/l makes it possible to inhibit the sensitive gram-positive bacteria without interfering with the detection of the ESBL bacteria.
• a concentration between 2 and 64 mg/l, and in particular 4 to 16 mg/l makes it possible to inhibit the sensitive gram-positive bacteria without interfering with the detection of the ESBL bacteria.
• the inhibition of the gram-positive bacteria made it possible to improve the detection of the ESBL bacteria in polymicrobial samples and the specificity of their coloration.
• a medium according to the invention can also comprise antifungals in order to inhibit the possible presence of yeasts which could grow on the medium and which could impair microorganism growth.
• amphotericin B under the conditions tested, a concentration between 1 and 32 mg/l, and in particular 2 to 8 mg/l, makes it possible to inhibit the sensitive yeasts without interfering with the detection of the ESBL bacteria.
• a concentration of between 1 and 64 mg/l, and in particular 4 to 16 mg/l makes it possible to inhibit the sensitive gram-positive bacteria without interfering with the detection of the ESBL bacteria.
• the inhibition of the yeasts made it possible to improve the detection of ESBL bacteria in polymicrobial samples and the specificity of their coloration.
• This second example is based on the phenotypic detection of ESBLs using the reduction of susceptibility to antibiotics and the sensitivity of HL Cases to combinations with tobramycin or cloxacillin or dicloxacillin, and presents the use of a cephalosporine mentioned above (CTX, CAZ, CPD, CRO, ATM) in combination with a compound that inhibits cephalosporinases (cloxacillin, dicloxacillin and tobramycin).
• CX, CAZ, CPD, CRO, ATM cephalosporinases
• Such a medium makes it possible to inhibit bacteria which have a “natural” cephalosporinase, most of those which have only a high level cephalosporinase (HL Case), while at the same time allowing growth of ESBL bacteria.
• the medium used was a CPS ID3 medium (43541), also comprising:
• Osmosed water is added and the whole is homogenized and melted in a waterbath at 100° C.
• the basic medium is dispensed into flasks, the number of which corresponds to the total number of media to be tested during the process.
• the flasks are then autoclaved for 15 min at 121° C.
• the media are brought back to and kept molten at 55 ⁇ 3° C. in a waterbath, in order to sterilely add the thermolabile additives (sterilized beforehand by filtration through 0.22 ⁇ m).
• the media are then poured into plates 35 mm in diameter and left on a flat surface so that they can set.
• the surface of the agars is then dried under a laminar flow hood for 30 min.
• This step is carried out as described in example 1.
• Medium A comprising ceftazidime and tobramycin made it possible to inhibit all the wild-type strains and all the HL Cases tested. Only the ESBL-positive strains were detected on this medium.
• Medium B comprising ceftriaxone and cloxacillin made it possible to inhibit all the HL Cases and all the wild-type strains except HL Case and wild-type P aeruginosa, and grew only the majority of the ESBL-positive strains.
• Medium C comprising cefpodoxime and di-cloxacillin made it possible to inhibit all the wild-type strains and the majority of the HL Cases, without affecting the growth of ESBL-positive strains.
• This third example is based on the phenotypic detection of enterococci resistant to glycopeptides, with specific distinction of Enterococcus faecalis and E. faecium, using the reduction of susceptibility to antibiotics and the demonstration of an enzymatic activity: ⁇ -glucosidase, and of a metabolic activity: Methyl- ⁇ -glucoside acidification.
• the medium used was a Columbia medium (51026), also comprising:
• Osmosed water is added and the whole is homogenized and melted in a waterbath at 100° C.
• the basic medium is dispensed into flasks, the number of which corresponds to the total number of media to be tested during the process.
• the flasks are then autoclaved for 15 min at 121° C.
• the media are brought back to and kept molten at 55 ⁇ 3° C. in a waterbath, in order to sterilely add the thermolabile additives (sterilized beforehand by filtration through 0.22 ⁇ m).
• the media are then poured into plates 90 mm in diameter and left on a flat surface so that they can set.
• the surface of the agars is then dried under a laminar flow hood for 30 min.
• This step is carried out as described in example 1.
• This step is carried out as described in example 1.
• the resistant E. faecalis and E. faecium strains form green colonies, whereas those of E. casseliflavus and of E. gallinarum form blue-to-violet colonies.
• This medium therefore makes it possible to differentiate these two groups of enterococci and to provide a suitable therapeutic response.
• This fourth example is based on the phenotypic detection of glycopeptide-resistant enterococci, with specific distinction of Enterococcus faecalis and E. faecium, using the reduction of susceptibility to antibiotics and the demonstration of two enzymatic activities: ⁇ -glucosidase and ⁇ -galactosidase or ⁇ -glucosidase.
• the media used were a Columbia medium (51026), also comprising:
• Osmosed water is added and the whole is homogenized and melted in a waterbath at 100° C.
• the two basic media are dispensed into flasks.
• the flasks are then autoclaved for 15 min at 121° C.
• the media are brought back to and kept molten at 55 ⁇ 3° C. in a waterbath, in order to sterilely add the thermolabile additives (sterilized beforehand by filtration through 0.22 ⁇ m).
• the media are then poured into plates 90 mm in diameter and left on a flat surface so that they can set.
• the surface of the agars is then dried under a laminar flow hood for 30 min.
• This step is carried out as described in example 1.
• This step is carried out as described in example 1.
• the resistant E. faecium strains form violet colonies, whereas the resistant E. faecalis strains form pink colonies.
• the E. casseliflavus and E. gallinarum strains are inhibited due to the concentration of vancomycin.
• This medium therefore makes it possible to differentiate these two groups of enterococci and to provide a suitable therapeutic response and also a follow-up of the local epidemiology.
• the resistant E. faecium strains form violet colonies, whereas the resistant E. faecalis strains form green colonies.
• the E. casseliflavus and E. gallinarum strains are inhibited due to the concentration of vancomycin.
• This medium therefore makes it possible to differentiate these two groups of enterococci and to provide a suitable therapeutic response and a follow-up of the local epidemiology.

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