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Bacillus cereus (MYP) agar is intended for the selective enumeration of Bacillus cereus in food samples. This medium utilizes two reactions namely mannitol fermentation and lecithinase production to differentiate Bacillus cereus from other related species. As B. cereus is mannitol negative the colonies are pink in colour due to the presence of the phenol red pH indicator. Lecithinase production (from the addition of egg yolk) is indicated by a white precipitate around the colonies. This medium meets the requirements of ISO 7932:2004. Beef extract and peptone provide the required carbon, nitrogen and vitamins. Sodium chloride helps maintain the osmotic balance and phenol red is the pH indicator. Mannitol is a fermentable carbohydrate. The medium is made selective by the inclusion of polymyxin B sulphate (LS0020). NB: This is a basic medium only and contains no additional supplement. It should be noted that some Proteus spp. and Gram-positive cocci may grow on this medium. Related Supplements : LS0020 Bacillus cereus Selective Supplement, BM0140 Egg Yolk Emulsion -
Bacillus cereus agar (PEMBA) is used for the selective isolation and enumeration of Bacillus cereus in food samples. It is said to be particularly suitable for the detection of small numbers of Bacillus cereus particularly in the presence of other contaminating organisms. Bacillus cereus agar (PEMBA) is based on the formulation developed by Holbrook and Anderson. The peptone provides the required carbon, nitrogen and vitamins. Mannitol is a fermentable carbohydrate. Bromothymol blue is a pH indicator used to detect mannitol fermentation. Sodium chloride maintains the osmotic balance. Magnesium sulphate provides divalent cations and sulphate. Di-sodium hydrogen phosphate and potassium dihydrogen phosphate are buffering agents. Egg yolk emulsion (BM0140) must be added to this media to assess lecithinase production. Sodium pyruvate is present to improve egg yolk precipitation and enhance B. cereus sporulation. The medium is made selective by the inclusion of polymyxin B sulphate (LS1051).
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Baird Parker agar is a selective medium for the isolation and presumptive identification of coagulase-positive staphylococci. This medium is used extensively for detecting Staphylococcus aureus in foods, dairy products, and other materials. Enzymatic digest of casein, meat extract and yeast extract provide the required carbon, nitrogen and vitamins. The medium is made selective by the inclusion of lithium chloride and the addition of potassium tellurite. Glycine and sodium pyruvate are included as growth enhancers while the pyruvate also acts as a neutraliser of toxic peroxides. Coagulase positive staphylococci are differentiated by the addition of egg yolk tellurite (BM0530) due to their ability to break down the egg yolk. Clear zones around colonies form due to the proteolytic action of lecithinase. A secondary opaque zone, surrounding presumptive positive colonies, may also form due to lipase activity. Potassium tellurite is reduced by staphylococci giving rise to blackening of colonies. NB: Any black colonies (with halo (typical) or without the halo (atypical)) on this medium must be confirmed as Staphylococcus aureus by further tests (e.g. coagulase test or latex agglutination etc.) Related Supplements : BM0530 Egg Yolk Tellurite
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Cetrimide agar is a selective medium for the isolation and detection of Pseudomonas aeruginosa from pharmaceutical, clinical and cosmetic samples. The formulation is complaint with the requirements of the Harmonised USP/EP/JP. Detection is achieved using the unique ability of P. aeruginosa to produce the water soluble, bright green pigment pyocyanin. The production of this pigment is stimulated by the presence of magnesium chloride and di-potassium sulphate in the medium. The addition of glycerol (10ml/l) is required as this compound serves as an energy source. Cetrimide, a quaternary ammonium compound, is also present to suppress the growth of other Pseudomonas spp. as well as Gram-negative and Gram-positive organisms. Pancreatic digest of gelatin provides the required nitrogen, carbon and vitamins. Related Supplements :
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KM0005 CLED Double Indicator Agar (Bevis) is a differential culture medium used clinically for isolation and enumeration of bacteria in urine, from the suspected cases of urinary tract infection (UTI). KM0005 CLED Double Indicator Agar (Bevis) is a differential culture medium which contains cystine, lactose, bromothymol blue, acid fuchsin and is electrolyte deficient to prevent swarming of Proteus species. Bevis changed the original medium by Mackey and Sandys by introducing a second pH indicator to enhance the differentiation of colony characteristics of lactose and non-lactose fermenting organisms. The medium can allow for quantitative determination of urinary pathogens, including Proteus species, when automated systems or calibrated loops are used for inoculation. KM0005 is recommended as a differential primary isolation media by the UK Standards for Microbiology Investigations and tested in accordance with ISO 11133:2014.
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E.E. Broth is recommended as an enrichment medium when examining food and feedstuffs for Enterobacteriaceae. It is a modification of Brilliant Green Bile Broth, with an improved buffering capacity to encourage early growth and prevent autosterilization. E.E. Broth uses glucose instead of lactose to make the medium a test for all enterobacteria including non-lactose fermenting organisms. This formulation complies with the Harmonized USP/EP/JP. Nitrogen is supplied by the gelatin peptone whilst glucose serves as the fermentable carbohydrate source. Oxbile and brilliant green are the selective agents helping to suppress Gram-positive non- target organisms. Auto sterilisation is prevented through the buffer system composed of potassium dihydrogen phosphate and disodium hydrogen phosphate.
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KM0006 Fastidious Anaerobe Agar is a general-purpose medium, when supplemented with blood and any necessary selective agents, can be used for the isolation and culture of fastidious anaerobes from clinical specimens. Anaerobic infections are common infections caused by anaerobic bacteria. These bacteria occur naturally and are the most common flora in the body; in their natural state, they do not cause infection. Anaerobic bacteria can infect deep wounds, tissue, and internal organs where there is little oxygen after injury or surgery. Infection by anaerobic bacteria is normally characterized by formation of abscesses, foul smelling discharge, pus, and free gas in tissue, leading to tissue degradation. KM0006 is recommended as a standard, primary isolation or supplementary medium by the UK Standards for Microbiology Investigations and tested in accordance with the principles of ISO 11133:2014. Related Supplements : LS0015 Actinomycete Selective Supplement, LS0017 Neomycin Selective Supplement, LS0022 Clostridium difficile Selective Supplement, LS0023 Clostridium perfringens Selective Supplement, BM0140 Egg Yolk Emulsion
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This medium is for the growth of fastidious anaerobes, particularly Bacteroides spp. Fastidious anaerobe broth is also suitable for anaerobic blood culture. The peptone and yeast extract provides the required carbon, nitrogen and vitamins. Haemin, vitamin k and L-cysteine HCl are growth factors required by some anaerobes. Sodium thioglycollate and L-cysteine HCl reduce the Eh of the medium and the agar helps maintain the Eh. Resazurin is a redox indicator and sodium chloride maintains the osmotic balance. NB: For best results it is recommended that the medium be heated in a boiling water bath, with the cap loosened, and then allowed to cool, with the cap tightened, immediately before use. The cap must be replaced on the container immediately after inoculation.
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Half-Fraser broth is a selective enrichment broth for the identification and isolation of Listeria spp., primarily from food and environmental samples. The antibiotics, nalidixic acid and acriflavine, are already included in the formulation so only ferric ammonium citrate (LS5004) need be added to make the complete Half-Fraser broth. The peptones provide carbon, nitrogen and vitamins, sodium chloride provides osmotic balance and the phosphate buffer system maintains pH. Lithium chloride inhibits enterococci and the antibiotics make the medium highly selective. Listeria spp. hydrolyse aesculin to aesculetin which forms a confirmatory dark brown or black complex with Fe3+ ions.
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KM0016 GC Agar is based on the formulation described by Thayer and Martin that was modified from the formulation development by Johnson for the isolation of gonococcus cultures and is recommended primarily for the isolation of Neisseria gonorrhoeae and Neisseria meningitidis; however, it is also capable of supporting the growth of most fastidious micro-organisms from clinical specimens, and is recommended by the UK Standards for Microbiology Investigations for a variety of clinical samples, and falls under the category of selective media for pathogenic Neisseria spp. according to the Clinical and Laboratory Standards Institute. Enrichment of KM0016 GC Agar is usually attained using lysed blood but haemoglobin powder or chocolated blood are suitable alternatives. Further enrichment may be provided by the addition of Suplex Supplement (E&O BM0478) which contains yeast extract and glucose. Selective plated media variants of KM0016 GC Agar, may be prepared by the addition of various selective supplements such as LCAT Selective Supplement (E&O LS0001) or VCAT Selective Supplement (E&O LS0002). These supplements suppress most microbiota present in clinical specimens. Related Supplements : BM0478 Suplex, LS0001 GC LCAT Selective Supplement, LS0002 GC VCAT Selective Supplement
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KM0215 Half Fraser Broth Complete is used to make Half Fraser Broth enrichment media for the isolation of Listeria species from food and environmental samples.
Developed in 1988 by Fraser (1), the formulation can be made as primary enrichment Half Fraser Broth and secondary enrichment Fraser Broth according to the requirements of ISO 11290-1:2017 (2). KM0215 is recommended by the International Standardization Organization (2) and tested in accordance with the principals of ISO 11133:2014 (3).
The nalidixic acid, acriflavine, and ferric ammonium citrate are already included in the formulation, so no additional supplements are required to make complete Half Fraser Broth.
- Fraser, J. and Sperber, W. (1988) Rapid Detection of Listeria spp. in Food and Environmental Samples by Esculin Hydrolysis. Journal of Food Protection, 51(10), pp.762-765. 2. International Standardization Organization (2017) 11290-1:2017 Microbiology of the food chain - Horizontal method for the detection and enumeration of Listeria monocytogenes and of Listeria spp. - Part 1: Detection method. Geneva: ISO. 3. International Standardization Organization (2014) 11133:2014 Microbiology of food, animal feed and water — Preparation, production, storage and performance testing of culture media. Geneva: ISO.
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Letheen agar modified is intended for use in the isolation of microorganisms from cosmetics. The casein peptone, meat peptone, beef extract and yeast extract act as carbon, nitrogen and vitamin sources in this medium. Glucose is a fermentable carbohydrate. Sodium chloride maintains the osmotic balance of the medium. The sodium bisulfite, lecithin and polysorbate 80 inactivates quaternary ammonium compounds. Polysorbate 80 neutralises phenols, formalin, hexachlorophene, and in combination with the lecithin, ethanol.
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Letheen broth modified is intended for use in the isolation of microorganisms from cosmetics. The enzymatic digest of animal tissue, enzymatic digest of casein, yeast extract and beef extract act as carbon, nitrogen and vitamin sources in this medium. Sodium chloride maintains the osmotic balance of the medium. The sodium bisulfite and lecithin inactivates quaternary ammonium compounds. Polysorbate 80 must be added to the medium prior to sterilisation. Polysorbate 80 neutralises phenols, formalin, hexachlorophene, and in combination with the lecithin, ethanol.
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Listeria isolation medium (Oxford) is based on the formulation described by Curtis et al. and is used for the isolation and identification of Listeria spp. in food and clinical laboratories. Columbia agar base provides the required carbon, nitrogen and vitamins in the medium. Lithium chloride is included to inhibit enterococci. Aesculin is present as an indicator; Listeria spp. will hydrolyse aesculin and the associated reaction with the ferric ammonium citrate gives rise to a black precipitate around the colonies. Selectivity is enhanced by addition of Listeria Oxford selective supplement (LS0030). This contains acriflavine, cefoxitin, colistin, fosfomycin and amphotericin to inhibit any yeasts present and some other Gram-positive and Gram-negative organisms that may be present in specimens. Related Supplements : LS0030 Listeria Oxford Selective Supplement
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Lowenstein-Jensen medium is based on the original formulation of Lowenstein that was subsequently modified by Jensen. It is used with fresh egg and glycerol for the isolation and presumptive identification of Mycobacterium spp., particularly Mycobacterium tuberculosis, from clinical samples. L-Asparagine and Potato starch are sources of nitrogen and vitamins in the medium. Potassium hydrogen phosphate and magnesium sulphate enhance organism growth and act as buffers. Sodium citrate and malachite green are selective agents that have inhibitory effects on organisms other than the mycobacteria. Malachite green is also incorporated into the medium to provide a colour contrast between the colonies and the medium. The required addition of egg emulsion provides the fatty acids and protein required for the metabolism of mycobacteria. Glycerol is also added which is said to enhance the growth of Mycobacterium tuberculosis however other strains of mycobacteria, particularly Mycobacterium bovis, may be inhibited by its presence. Subsequently, sodium pyruvate (12.5 g/600ml) may be used as an alternative to glycerol to encourage the growth of Mycobacterium bovis.
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Palcam agar is a selective differential medium for the isolation of Listeria monocytogenes from food, clinical and environmental specimens. The Columbia peptone mix and starch provide the required carbon, nitrogen and vitamins. Glucose is a fermentable carbohydrate. Differentiation of Listeria spp. from enterococci and staphylococci occurs through aesculin hydrolysis and mannitol fermentation. Listeria monocytogenes will hydrolyse aesculin and the associated reaction with the ferric ammonium citrate gives rise to a brown/black precipitate around the colonies. Listeria spp. do not however ferment mannitol. Mannitol fermentation is seen through a colour change of the colony or the area around the colony from red to yellow due to the production of acidic end products. Phenol red is the pH indicator in the medium. Lithium chloride is included to inhibit enterococci. The associated Palcam selective supplement, LS0038, contains polymyxin B, acriflavine and ceftazidime to inhibit other Gram-positive and Gram-negative organisms that may be present in specimens. Related Supplements : LS0038 PALCAM Selective Supplement
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Peptone water is a general-purpose medium that supports thecultivation of non-fastidious organisms. This non-selective medium can be used a basal medium for biochemical tests such as carbohydrate fermentation and production of indole. Tryptone and peptone act as sources of carbon, nitrogen and vitamins in this medium and sodium chloride maintains osmotic balance.
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KM0058 Primary Listeria Agar is a selective medium for the isolation, enumeration and presumptive identification of Listeria species and L. monocytogenes from food and environmental samples. Listeria monocytogenes is commonly found in soil, sewage, and faeces. It is difficult to eradicate, and can cause serious food poisoning; therefore, L. monocytogenes is frequently tested for in food processing facilities to avoid contamination. Contamination can occur at all steps of the food manufacturing chain from raw materials to point of consumption. Primary Listeria Agar is used for the detection and presumptive identification of Listeria spp. and the specific differentiation of L. monocytogenes. Based on the method of Ottaviani et al (1 2), this medium allows detection and enumeration of Listeria spp. as early as 24 hours. Primary Listeria Agar is recommended by ISO 11290-1:2017 (3) and ISO 11290-2:2017 (4) and tested in accordance with ISO 11133:2014 (5). References:- Ottaviani, F., Ottaviani, M., and Agosti M. (1997) Differential agar medium for Listeria monocytogenes. Quimper Froid Symposium Proceedings, P6 ADRIA Quimper, France, 16-18 June.
- Ottaviani, F., Ottaviani, M.G., and Agosti, M. (1997). Esperienze su un agar selettivo e differenziale per Listeria monocytogenes. Industrie Alimentari, 36: 888-889.
- International Organization for Standardization (2017) 11290-1:2017 Microbiology of the food chain – Horizontal method for the detection and enumeration of Listeria monocytogenes and of Listeria spp. – Part 1: Detection method. Geneva, ISO.
- International Organization for Standardization (2017) 11290-2:2017 Microbiology of the food chain – Horizontal method for the detection and enumeration of Listeria monocytogenes and of Listeria spp. – Part 2: Enumeration method. Geneva, ISO.
- International Organization for Standardization (2014) 11133:2014 Microbiology of food, animal feed and water – Preparation, production, storage and performance testing of culture media. Geneva, ISO.
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R2A agar is used for the enumeration and cultivation of bacteria from drinking water. R2A agar developed by Reasoner and Geldreich is a low nutrient medium that can used in pour plate, spread plate, and membrane filtration methods for heterotrophic plate counts. In combination with a lower incubation temperature and longer incubation period R2A agar stimulates the growth of stressed and chlorine-tolerant bacteria. Traditionally nutritionally rich media have been used for this purpose but these media support the growth of fast-growing bacteria and may suppress slow growing or stressed bacteria found in treated water. Enzymatic digest of casein, proteose peptone, acid hydrolysate of casein and yeast extract provide the required nitrogen, carbon and vitamins. Glucose is a fermentable carbohydrate. Dipotassium hydrogen phosphate is a buffering agent. Magnesium sulphate is a source of divalent cations and sulphate. Starch and sodium pyruvate aid in the recovery of stressed organisms.
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This medium was originally described by Slanetz and Bartley(1) for the enumeration of enterococci from water samples using membrane filtration. The medium has also become useful as a direct plating medium. Tryptose and yeast extract provide the required carbon, nitrogen and vitamins. Glucose is a fermentable carbohydrate. The di-potassium hydrogen phosphate acts as a buffer. Selectivity is achieved through the addition of sodium azide which is used to suppress the growth of Gram-negative organisms. The medium contains tetrazolium chloride, which is reduced by enterococci to the insoluble red dye formazan resulting in dark red colonies of enterococci on the agar. It should be noted that this reaction is not exclusive to enterococci and colonies should be confirmed by additional testing e.g. aesculin hydrolysis.
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Recent developments in culture media have given rise to the use of chromogenic substrates as a means of differentiating bacteria particularly among the coliform group of organisms. This is one such medium and has been developed as a selective medium for the isolation and enumeration of Escherichia coli without the need for membranes or pre-incubation. Based on the formulation of Tryptone Bile Agar it incorporates a chromogenic substrate, X-Glucuronide, to detect the ß-glucuronidase enzyme which is specific for the majority of E. coli strains. Approximately, 3-4% of E. coli are glucuronidase negative including E. coli O157.(1) The advantage of the chromogenic substrate is that the reaction is concentrated within the colony resulting in distinctive blue/green colonies of E. coli while the other coliforms produce cream colonies. The tryptone provides the required carbon, nitrogen and vitamins. Bile salts No.3 is a selective agent against Gram-positive bacteria. X-glucuronide is a chromogenic substrate. Agar is solidifying agent.
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Yeast extract agar is a nutrient rich medium for the cultivation of non-fastidious bacteria, yeasts and moulds. Recommended for the plate count of microorganisms in water and dairy products. The yeast extract and peptone acts as a source of nitrogen, amino acids, carbon and vitamins. Related Supplements : LS0019 Oxytetracycline Selective Supplement
