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Pasteurella Agar Base is an non-selective medium capable of supporting the growth of Pasteurella spp. Pasteurella spp.are spherical, ovoid or rod-shaped cells 0.3-1.0μm in diameter and 1.0-2.0μm in length. Cells are Gram negative, and occur singly, or in pairs or short chains. Bipolar staining may be seen and capsules may be present. All species are non-motile, and are facultatively anaerobic.(1) With further enrichment using 5-10% blood and selective antimicrobials, most Pasteurella spp. can be isolated. There is no haemolysis on blood agar for Pasteurella spp. and the organism will not regularly exhibit satellitism around colonies of Staphylococcus spp. The peptones act as carbon, nitrogen and vitamin sources in this medium. Sodium chloride maintains the osmotic balance and the agar is a solidifying agent. The medium is made selective through the addition of LS0057, Pasteurella agar selective supplement. REFERENCE (1) Standards Unit, Microbiology Services, PHE. 1995. UK Standards for Microbiology Investigations. Identification of Pasteurella species and Morphologically Similar Organisms. 3, 1-28. -
Perfringens Agar Base is a base medium that allows the enumeration of Clostridium perfringens from food samples. As a base medium, Perfringens Agar Base can have several supplementary and selective agents added to increase selectivity. The addition of Eye Yolk Emulsion (BM0140) allows the detection of lecithinase activity as precipitates are formed by C. perfringens. The addition of D-cycloserine (LS0023) can be used to inhibit other facultative anaerobes, as used in Tryptose-Sulphite-Cycloserine (TSC) agar. (1&2) Alternately, kanamycin and polymyxin B (LS0025) can be used to inhibit other coliforms generally found in food samples, as used in Shahidi-Ferguson Perfringens (SFP) agar.(3) The tryptose and soy peptone provide the required nitrogen, carbon and minerals. Yeast extract provide the essential vitamins, including the vitamin B group, needed for growth. The ferric ammonium citrate and sodium metabisulphite allows the reduction of sulphites to hydrogen sulphide by C. perfringens, which produces black colonies. References (1) ISO- 7937:2004. Microbiology of food and animal feeding stuffs- Horizontal method for the enumeration of Clostridium perfringens - Colony count technique (2) Harmon, S.M., Kauttar, D.A. and Peeler, J.T. 1971. Improved Medium for Enumeration of Clostridium perfringens. Appl. Microbiol. 22:688-692. (3) Shahidi S. A. and Ferguson A. R. 1971 New Quantitative, Qualitative, and Confirmatory Media for Rapid Analysis of Food for Clostridium perfringens. Appl. Microbiol. 21:500-506
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Plate Count Agar is formulated to the A.P.H.A. specification developed by Buchbinder et al. This medium is intended for use in food, dairy and water bacteriology to perform Total Viable Counts. Tryptone and yeast extract provide the required carbon, nitrogen and vitamins. Glucose is a fermentable carbohydrate.
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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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Primary Membrane Lactose Glucuronide Agar (mLGA) is used for the differentiation and enumeration of Escherichia coli and other coliforms through a single membrane filtration technique. The peptone and yeast extract provide the required nitrogen, carbon and vitamins. Sodium pyruvate protects injured cells enhancing recovery and growth of coliforms. Sodium lauryl sulphate is a selective agent that inhibits Gram-positive organisms. Lactose is a fermentable carbohydrate and phenol red is a pH indicator. Lactose fermentation will result in yellow colonies. X-glucuronide is a chromogenic substrate which can be cleaved by the enzyme ß-glucuronidase present in E. coli. This results in a blue colony, but in combination with lactose fermentations colonies will appear green. NB: Prepared plates stored at 28°C may show formation of surface crystals which will disappear when plates are warmed to >20°C Related Supplements :
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KM0007 Primary UTI Agar is a chromogenic agar that has been developed to allow differentiation and presumptive identification of organisms typically found in urinary tract infections. Urinary Tract Infections (UTI’s) account for 35-40% of all hospital acquired infections in the UK. Gram negative aerobic bacteria are responsible for a considerable proportion of UTI’s with Escherichia coli isolation rates at 80-90% of first-time infections. Various other opportunistic bacterial species can cause UTI’s. KM0007 may be used as a chromogenic medium for the quantification and presumptive identification of bacteria in urine from clinical samples in line with the UK Standards for Microbiology Investigations and tested in accordance with the principles of ISO 11133:2014. Related Supplements : SHS500 Sterile Horse Serum 500ml
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KM0079 Pseudomonas Agar Base with the addition of supplements, is a selective medium for the isolation of Pseudomonas species primarily from clinical, food, water, and environmental samples. The medium can be made selective for Pseudomonas aeruginosa by the addition of E&O LS0006 Pseudomonas Selective Cetrimide and Nalidixic Acid Supplement which complies to ISO 16266:2006 and ISO 11133:2014. Alternatively, the medium can be made selective for Pseudomonas species by the addition of E&O LS0026 Pseudomonas CFC Selective Supplement which complies to ISO 13720:2010 and can be used as a primary isolation medium according to Public Health England’s UK Standards for Microbiology Investigations. Identification is achieved using the unique ability of P. aeruginosa to synthesise the iron chelating pigments pyoverdin and pyocyanin which combine to produce the characteristic green colonies of Pseudomonas aeruginosa. Production of these pigments is stimulated by the presence of magnesium and potassium ions in the medium. The presence of blue/green or brown pigmentation or fluorescence is indicative of presumptive Pseudomonas species. It should be noted however that further testing must be conducted to confirm the full identity of the organism.
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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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KM0003 Sabouraud Dextrose Agar powder is a general-purpose, non-selective medium which is used for the isolation of yeasts and moulds from clinical, food, pharmaceutical and cosmetic samples. Sabouraud Dextrose Agar is a modification of a medium originally described by Sabouraud. The fungi maintain their typical cultural appearance and thus may be readily identified according to the standard macroscopic characters described by Sabouraud. The formulation conforms to European, United States and Japanese Pharmacopeia requirements. This medium complies with ISO 11133:2014, where it is described as the main reference medium to carry out quantitative testing on culture media intended for fungi. Sabouraud Dextrose Agar is recommended by the UK Standards for Microbiology Investigations for various purposes, including as a standard, supplementary or optional medium. Related Supplements : LS0050 Chloramphenicol Selective Supplement
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Sabouraud dextrose agar with chloramphenicol is a selective media for the isolation of yeasts and fungi suitable for use in all areas of mycology. Sabouraud dextrose agar is a modification of a medium originally described by Sabouraud.(1) The tryptone and meat peptone provides the required nitrogen, carbon and vitamins. The high concentration of dextrose is included as an energy source and in tandem with the acidic pH (5.6) facilitates the growth of fungi whilst providing limited selective properties.(2) Chloramphenicol is included to increase the selectivity of the media inhibiting a range of Gram-positive and Gram-negative bacteria. References (1) Sabouraud, R. 1892. Ann. Dermatol. Syphilol. 3:1061. (2) Jarett, L., and A. C. Sonnenwirth (eds.). 1980. Gradwohl’s and parasitic infections, 7th ed. American Public Health Association, Washington, D.C.
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This is a selective medium for the isolation of Salmonella spp. and Shigella spp. from clinical specimens and food samples. SS agar is a modification of the original DCA medium described by Leifson. The formulation for SS agar was later modified to improve the growth of Shigella spp. SS agar modified differs from SS agar in that it has an alternation to the bile salts mixture, peptone, pH value, and total g/litre. The peptone provides the required carbon, nitrogen and vitamins. Lactose is a fermentable carbohydrate and neutral red is a pH indicator. Sodium thiosulphate and ferric citrate are used to detect hydrogen sulphide production indicated by the black centred colonies of hydrogen sulphite positive organisms. Bile salts, sodium citrate and brilliant green inhibit Gram-positive bacteria and a number of different coliform bacteria.
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Sheep Blood Agar Base has been developed to provide a nutrient rich medium compatible with sheep blood for the cultivation of many bacteria, especially fastidious Streptococcus spp., without affecting haemolytic reactions. Alternative culture mediums, such as Blood agar base No. 2, can results in mixed haemolytic reactions for some Streptococcus spp. This is thought to occur due to the trace amounts of fermentable carbohydrates in yeast extract and the physiological difference between sheep and horse blood. The tryptone, peptone, and yeast extract provide the required nitrogen, carbon and vitamins in the medium. Sodium chloride maintains the osmotic balance. Related Supplements : LS0008 Staph/Strep Selective Supplement
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This medium can be used as a screening method for the differentiation of enterobacteriaceae based on the ability of some species to utilise citrate as a sole source of carbon. It is often used as a screening test for Klebsiella pneumoniae (positive reaction) while Escherichia coli is negative. Species that metabolize citrate as their sole source of carbon and ammonium as the sole source of nitrogen cause an increase in alkalinity of the medium resulting in a colour change from green to blue due to the presence of the pH indicator bromthymole blue.
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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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Sorbitol MacConkey agar is a differential medium for the isolation of Escherichia coli 0157:H7 based on the formulation by Rappaport and Henig. It differs from other MacConkey mediums in that lactose has been replaced by sorbitol. As Escherichia coli 0157:H7 does not ferment sorbitol it produces pale translucent colonies whereas most other strains of Escherichia coli are sorbitol positive and produce pink colonies. Although it should be noted that colonies that are sorbitol positive can revert and possibly be mistaken as sorbitol negative. Tryptone and meat peptone provide the required carbon, nitrogen and vitamins. Sorbitol is a fermentable carbohydrate and neutral red is a pH indicator. Bile Salts no.3 and crystal violet are selective agents and together inhibit Gram-positive cocci. Sodium chloride maintains the osmotic balance. If required, the selectivity of the medium may be increased by the addition of cefixime (0.05mg/L) and potassium tellurite (2.5mg/L). Related Supplements : LS0013 Escherichia coli 0157 Selective Supplement
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Thiosulphate Citrate Bile Salts Sucrose (TCBS) Agar is a selective isolation medium for culture of pathogenic Vibrio spp. from clinical and food samples. The formulation was developed by Kobayashi et al. which was modified from Nakanishi’s formulation. Vibrio species are most widely recognized for their role in human intestinal infections and cholera worldwide. Thiosulphate Citrate Bile Salts Sucrose (TCBS) Agar is recommended by the FDA BAM, the UK Standards for Microbiology Investigations, and complies with the standard laid out by ISO 21872.
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Triple sugar iron agar is used to differentiate between some of the enterobacteriacae on the basis of four reactions: fermentation of lactose, glucose and sucrose and the production of hydrogen sulphide. Beef extract, yeast extract and peptone provide the required nitrogen, carbon and vitamins. Lactose, sucrose and glucose are carbohydrates. Acid production from their fermentation is detected by the phenol red pH indictor. Sodium thiosulphate is reduced to hydrogen sulphide which is detected by the ferric citrate indicator. Sodium chloride maintains osmotic balance.
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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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Tryptone Soya Agar is used for a wide range of applications, including culture storage, enumeration of cells, isolation of pure cultures, or simply general culture. It has been found to be useful in cosmetic testing, water, and wastewater applications. Tryptone Soya Agar may be used to determine X and V factor requirements of Haemophilus species; sterility testing; and environmental monitoring within pharmaceutical cleanrooms and sterile facilities. This medium meets the requirements of the Harmonized USP/EP/JP and is based on the original formulation described by Leavitt et al. in 1955. Tryptone Soya Agar is recommended as a reference medium when testing selective media, to measure the degree of inhibition. In environmental monitoring applications, it is common for plates to be incubated at 30-35°C for bacterial colonies and 20-25°C for mould and fungi. Tryptone Soya Agar will support the growth of both aerobic and anaerobic organisms depending on incubation conditions. KM0024 unsupplemented is recommended by the World Health Organization, UK Standards for Microbiology Investigations, International Organization for Standardization and is tested in accordance with ISO 11133:2014. This medium is also included in the Bacteriological Analytical Manual for cosmetics testing. UK Standards for Microbiology Investigations also call for Tryptone Soya Agar supplemented with 5% sheep blood (E&O DSC) for aid in the identification of Bordetella species from clinical specimens. The addition of defibrinated animal blood to the base medium, promotes the growth of most fastidious organisms and presumptive identification can be made based on haemolytic reactions. It should be noted that the haemolytic patterns of isolates may vary with the source of animal blood. Addition of selective agents allows isolation and presumptive identification of specific species or groups of organisms. Related Supplements : Defibrinated Sheep Blood, Defibrinated Horse Blood
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A modification of Christensens medium by Maslen this medium is generally used to detect rapid urease activity of Proteus spp. It can also be used to detect urease activity of other enterobacteriaceae including urease producing Salmonella spp. and Shigella spp. When used for the latter purpose it is necessary to increase the incubation time to as long as 48 hours. The peptone provides the required nitrogen, carbon and vitamins. Glucose is a fermentable carbohydrate. The potassium dihydrogen phosphate is a buffer and sodium chloride maintains osmotic balance. Phenol red is a pH indicator. Related Supplements : BM3000 Urea 40% Solution
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Violet Red Bile Agar is a medium for the enumeration of coliform organisms in food and dairy products and conforms to American Public Health Association (APHA). Yeast extract and enzymatic digest of gelatin provides the required carbon, nitrogen and vitamins. Sodium chloride maintains the osmotic balance. The medium is made selective by the inclusion of bile salts and crystal violet to inhibit Gram-positive and non-enteric organisms. Lactose is a fermentable carbohydrate and neutral red is a pH indicator. Lactose fermenters produce red/purple colonies often surrounded by a halo of the same colour. Non lactose fermenters produce pale colonies. Selectivity can be increased by incubation at 42-44ºC.
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Violet Red Bile Glucose Agar (VRBGA) is a selective medium for the isolation and enumeration of Enterobacteriaceae in food products. It is a modification of the original Violet Red Bile Agar with the lactose being replaced with glucose. As all Enterobacteriaceae ferment glucose VRBGA allows for a wider range of organisms to be detected. This medium conforms to the requirements of the Harmonised USP/EP/JP. Yeast extract and pancreatic digest of gelatin provide the required carbon, nitrogen and vitamins. Glucose is a fermentable carbohydrate and neutral red is a pH indicator. Sodium chloride maintains the osmotic balance. The medium is made selective by the inclusion of bile salts and crystal violet to inhibit Gram-positive and non-enteric organisms.
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KM0013 Xylose Lysine Deoxycholate (XLD) Agar is used for the isolation and detection of Salmonella and Shigella spp. in clinical specimens, food, and environmental samples. Xylose Lysine Deoxycholate (XLD) Agar is used for the isolation of Salmonella from food and animal feedstuffs when used according to ISO 6579:2017, ISO 11133:2014. The formulation conforms to CLSI M22 and European, United States and Japanese Pharmacopeia requirements. KM0013 is recommended for clinical specimens as a standard, supplementary or primary isolation medium by the UK Standards for Microbiology Investigations. Xylose Lysine Deoxycholate (XLD) Agar has a pH of 7.4, leaving it with a bright red appearance due to the indicator phenol red. Sugar fermentation lowers the pH and the phenol red indicator registers this by changing to yellow. Most gut bacteria, including Salmonella spp., can rapidly ferment the sugar xylose to produce acid; Shigella spp. cannot do this and therefore remain red. Once the xylose has been used, Salmonella spp. decarboxylate lysine leading to a reversion to an alkaline pH. Additionally, Salmonella spp. (but not Shigella species) are able to reduce thiosulphate to hydrogen sulphide which reacts with ferric ions to produce the black pigment iron sulphide. Salmonella spp. may, therefore, be differentiated since colonies have a black centre on this medium.
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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
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This is a selective medium for the isolation and enumeration of yeasts and moulds in dairy products. It is in according to a typical formulation of The International Organisation for Standardisation (ISO). Yeast extract acts as a source of nitrogen, carbon and vitamins in this medium. Glucose is a fermentable carbohydrate. Although the medium has a low pH it is made more selective by the inclusion of chloramphenicol, an antibiotic selective agent.
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In vitro diagnostic. Dehydrated KM0179 Yersinia Selective Agar Base powder can be reconstituted to form a selective plated medium for the isolation and enumeration of Yersinia species from clinical and food samples.
