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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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KM0034 Blood Agar Base No. 2 is a general-purpose medium with is designed to be enriched with various concentrations of horse or sheep blood and is suitable for the isolation of most organisms including many fastidious anaerobes of clinical significance. Blood Agar Base No. 2, frequently shortened to BAB No.2, was developed to meet the demand for an especially nutritious blood agar base which would permit the maximum recovery of delicate organisms, such as streptococci, pneumococci, and other fastidious microorganisms, without interfering with their haemolytic reactions. Haemolysis observations may vary with the type of blood being used and previous studies have shown that sheep blood provides the most reliable colony and haemolysis characteristics. When the blood is chocolated the medium gives good recovery of Haemophilus species. KM0034, when prepared with required blood type, is recommended as a non-selective blood agar by UK Standards for Microbiology Investigations and is tested in accordance with the principals of ISO 11133:2014 . Related Supplements : Defibrinated Sheep Blood, Defibrinated Horse Blood, LS0008 Staph/Strep Selective Supplement, LS0017 Neomycin Selective Supplement
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Brain heart infusion agar is very nutritious general-purpose medium and is suitable for the isolation of most micro-organisms including many fastidious organisms. The formulation is a modification of that from Rosenow and Hayden. The medium is not recommended for the determination of haemolytic reactions because of the glucose content. The nitrogen, vitamin and carbon sources are supplied by the Brain-Heart infusion solids and peptone. Glucose serves as the carbohydrate source and sodium chloride aids in maintaining the osmotic balance. A phosphate buffer, disodium hydrogen phosphate, is incorporated to help neutralize any acids produced as a result of glucose utilization and thus maintain viability of the organisms. NB: Organisms that produce large amounts of acid in the medium may overwhelm the buffering system and as a result may ‘auto-sterilize’ the culture.
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KM0038 Brilliant Green Agar is used for the selective isolation of Salmonella species from clinical specimens and food samples. Brilliant Green Agar was first cited by Kristensen et al. and later modified to improve selectivity. The medium is highly selective and may not be suitable for the isolation of Salmonella spp. from samples where numbers of salmonellae are low. If this is suspected to be the case, or if the sample is suspected to contain Salmonella typhi, other selective media such as Xylose Lysine Deoxycholate (XLD) Agar (E&O KM0013), Hektoen Enteric Agar (E&O KM0032) or Deoxycholate Citrate Agar (E&O KM0050) may be inoculated with the specimen in parallel. The United States Pharmacopeia indicates that the medium may be used to confirm the absence of salmonellae in nutritional and dietary supplements. The medium may also be used as a secondary plating medium for subculture from selective enrichment media during food and environmental testing, and as a primary isolation medium in the identification of Salmonella species from clinical specimens according to Public Health England’s UK Standards for Microbiology Investigations.
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Brucella Medium Base is a general purpose medium for the cultivation of Brucella spp. and other fastidious microorganisms. Brucella Medium Base has been developed from the APHA formulation for Albimi broth. The peptones act as carbon, nitrogen and vitamin source in this medium. Glucose is a fermentable carbohydrate and sodium chloride maintains the osmotic balance of the medium.
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Burkholderia cepacia agar base is a selective medium for the detection and isolation of Burkholderia cepacia from cystic fibrosis (CF) patients. This is an important opportunistic pathogen in CF patients and can lead to fatal infection in approximately 20% individuals that have been colonised with B. cepacia complex organisms. This medium is based on the PC medium described by Gilligan et al. Magnesium sulphate, ammonium sulphate and ferrous ammonium sulphate supports the growth of B. cepacia. Potassium di-hydrogen phosphate and di-sodium hydrogen phosphate are buffering agents, used to maintain the pH the medium. The phenol red is used as a pH indicator. If the sodium pyruvate in the medium is metabolised by B. cepacia alkaline by-products are produced which raises the pH. This causes the colour of the medium to turn pink/red around sections of heavy growth on the medium. Bile salts and crystal violet are selective agents. The associated selective supplement for this medium, LS0125, contains ticarcillin and polymyxin B which further improves the selectivity, particularly with the inhibition of Pseudomonas spp. Related Supplements : LS0125 B.cepacia Selective Supplement, LS0026 Pseudomonas CFC Selective Supplement
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KM0057 Campylobacter (CCDA) Agar is a selective medium for the isolation of Campylobacter spp., particularly C. jejuni and C. coli, from clinical specimens and foodstuffs. Campylobacter (CCDA) Agar was described by Bolton et al. and formulated to replace blood with a combination of charcoal, ferrous sulphate, and sodium pyruvate. This product is recommended for the isolation of Campylobacter spp. and complies with the requirements of ISO 10272-1:2017, ISO 10272-2:2017, is tested in accordance with ISO 11133:2014, and is a recommended medium in the UK Standards for Microbiology Investigations for isolation of Campylobacter spp. from clinical specimens such as faeces. Bolton et al. recommended incubating inoculated plates at 37°C to improve isolation rates, but incubation at 41.5°C is recommended for the isolation of the commonly encountered thermophilic species (C. jejuni and C. coli). Selectivity is achieved through the addition of E&O LS0010 Campylobacter CCDA Selective Supplement, which includes a broad-spectrum antibiotic, cefoperazone, and amphotericin B to inhibit yeast and fungi.
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This is one of several selective media available for the isolation of Campylobacter spp. in clinical, food and environmental laboratories. Campylobacter agar base is based on the formulation from Bolton and Robertson. The peptone is the source of the required nitrogen, carbon and vitamins. Sodium chloride maintains the osmotic balance in the medium. The medium is enriched with lysed horse blood and made selective by the addition of cefoperazone, to suppress other enteric organisms, and amphotericin to suppress yeast and fungal growth (Preston supplement LS0010). Related Supplements : LS0009 Campylobacter (Skirrow) Selective Supplement, LS0010 Campylobacter (Preston) Selective Supplement, Lysed Blood
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This medium is based on the formulation published by Platt, Atherton & Simpson1 and is used for the cultivation of Taylorella equigenitalis, the causative organism in contagious equine metritis. It is routinely used for culturing swabs taken from the genitalia of mares and stallions. Enzymatic digest of casein and soy peptone supply nitrogen, carbon and vitamins and L-cystine is a required growth factor. Sodium chloride provides osmotic balance and sodium sulphite is present as a reducing agent. The medium is made selective by the addition of CEMO Selective Supplement (LS0041) to control bacteria and fungi from swab samples. References 1. Platt, H., Atherton, J. G. and Simpson, D. J. 1978. Equine Vet J 10, 153–159.
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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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Charcoal agar is used for the cultivation of fastidious organisms, particularly Bordetella pertussis. Charcoal agar is prepared according to the formulation developed by Mishulow, Sharpe and Cohen. This medium is an efficient substitute for Bordet-Gengou agar in the production of B. pertussis vaccines and can be used as a maintenance medium for stock cultures of Bordetella spp. Beef extract and peptone provide the required nitrogen, carbon and vitamins. Sodium chloride maintains the osmotic balance. Starch and charcoal help in absorbing toxic metabolites that are produced during growth of the organism. Nicotinic acid is an essential growth factor for the growth of Bordetella spp. The addition of cephalexin (LS0018) inhibits accompanying contamination in the samples. NB: This is a basic medium only and contains no additional supplement. If cephalexin is added, it should be noted, that although coliforms are inhibited by this medium, Pseudomonas aeruginosa and some fungi will grow. Related Supplements : LS0018 Bordetella Selective Supplement
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Chromogenic coliform agar (CCA) conforms to the ISO 9308-1 guidelines for the detection, enumeration and isolation of coliforms and more specifically Escherichia coli in water samples by the membrane-filtration technique. The colonial differentiation is provided by the chromogenic substrates, Salmon-GAL and X-glucuronide. Salmon-GAL is used for the detection of ß-D-galactosidase enzymatic activity. X-glucuronide is used for the detection of ß-D-glucoronidase enzymatic activity. β-D-galactosidase, expressed by all coliforms, cleaves the Salmon-GAL substrate and producing red/pink coloured colonies. Unlike other coliforms, Escherichia coli cleaves both Salmon-GAL and X-glucuronide producing a violet/blue coloured colonies. Tryptophan is used to increase detection reliability by improving the indole reaction. The peptones, sodium pyruvate and sorbitol support bacterial growth and simple recovery of sub-lethal thermally injured coliforms. Sodium di-hydrogen phosphate and di-sodium hydrogen phosphate phosphate buffer the medium and sodium chloride is used to achieve osmotic balance. The selectivity is attained by the addition of Tergitol® 7 as it inhibits the growth of Gram-positive bacteria.
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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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KM0004 CLED Single Indicator Agar is a differential culture medium used clinically for isolation and enumeration of bacteria in urine, from the suspected cases of urinary tract infection (UTI). Originally described by Sandys, CLED (Cystine Lactose Electrolyte Deficient) Single Indicator Agar is a differential medium which contains cystine, lactose, bromothymol blue and is electrolyte deficient to prevent swarming of Proteus species. The medium can allow for quantitative determination of urinary pathogens, including Proteus species, when automated systems or calibrated loops are used for inoculation. KM0004 is recommended as a differential primary isolation media by the UK Standards for Microbiology Investigations and tested in accordance with the principals of ISO 11133:2014.
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Clostridium difficile agar, when supplemented, is used for the isolation of C. difficile from samples. This formulation is a modification of CCFA (Cycloserine-Cefoxitin-Fructose agar) developed by George et al. The proteose peptone act as carbon, nitrogen and vitamin source in this medium. Fructose is a fermentable carbohydrate. Sodium chloride maintains the osmotic balance of the medium. Disodium hydrogen phosphate and potassium dihydrogen phosphate are buffering agents. The magnesium sulfate acts as a source of inorganic ions and the agar is the solidifying agent. This media requires the addition of defibrinated horse blood and Clostridium difficile selective supplement (LS0022).
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KM0001 Columbia Agar is a modification of the original Columbia Agar formulation described by Ellner et al. from Columbia University and is tested in accordance with ISO 11133:2014. Columbia Agar provides a medium that is suitable for use with both defibrinated horse and sheep blood to support the growth and determining haemolytic reactions of a variety of microorganisms. Columbia Agar with the addition of plain or chocolated blood is recommended by the UK Standards for Microbiology Investigations for various purposes, including as a standard, supplementary or primary isolation medium. Columbia agar with blood is a general-purpose, non-selective medium suitable for isolation and cultivation of most organisms including fastidious anaerobes from clinical specimens. Chocolating the blood provides a highly nutritious medium which supports the growth of a wide range of pathogens including the most fastidious organisms and is particularly useful for the cultivation of Haemophilus and Neisseria species. Chocolate agar is the same as blood agar except that during preparation the red blood cells are lysed when added to molten agar base, which gives the medium a chocolate-brown colouration and from which the agar gets its name. As a result, cell lysis releases intracellular nutrients such as haemoglobin, haemin (X factor), and the coenzyme nicotinamide adenine dinucleotide (NAD or V factor) into the agar. These growth factors are available to fastidious organisms during growth. Related Supplements : Defibrinated Horse Blood, Defibrinated Sheep Blood, Horse Blood Lysed, LS0008 Staph/Strep Selective Supplement, LS0017 Neomycin Selective Supplement, LS0022 Clostridium difficle Selective Supplement, LS0012 Bacitracin Selective Supplement, LS0011 Campylobacter Growth Supplement, LS0009 Campylobacter (Skirrow) Selective Supplement
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This medium is used for the cultivation and enumeration of Lactobacillus spp. MRS agar is based on the formulation by de Man, Rogosa and Sharpe. The peptone, yeast extract and beef extract provides the reuired carbon, nitrogen and vitamin source. Glucose is a fermentable carbohydrate. The magnesium sulphate and manganese sulphate act as growth stimulants. Potassium phosphate is a buffering agent. Selectivity of the medium is achieved through the use of ammonium citrate and sodium acetate, inhibiting microorganisms such as streptococci and moulds. The addition of the surfactant Tween 80 is required to facilitate the uptake of nutrients from Lactobacillus spp.
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This is a selective medium for the isolation of Salmonella spp. and Shigella spp. from clinical specimens and environmental samples. This formulation was developed by Hynes through a modification of Leifson’s DCA medium. 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. Sodium deoxycholate and sodium citrate inhibit most Gram-positive organisms.
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A selective medium for the isolation and detection of dermatophytic fungi originally developed by Taplin et al. Dermatophytes appear as fluffy colonies with reddening of the medium while other fungi cause the medium to become yellow due to acid production. Yeasts will also grow on this medium but are readily distinguished by their distinct white/creamy colonies and distinctive smell. Soy peptone provides the required carbon, nitrogen and vitamins. Glucose is a fermentable carbohydrate. The inclusion of phenol red assists in the differentiation between saprophytic and environmental fungi. Although the low pH (pH 5.5) of the medium inhibits most bacteria chloramphenicol and cycloheximide are often added to further reduce the risk when processing material that may be more heavily contaminated. NB: Prolonged incubation should be avoided as this may cause fungi other than dermatophytes to turn the medium red. Related Supplements : LS0050 Chloramphenicol Selective Supplement
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Dichloran Rose Bengal Chloramphenicol (DRBC) agar is based on the formulation described by King et al. and is used for the selective isolation and enumeration of yeasts and moulds from food samples. The peptone provides the required carbon, nitrogen and vitamins. Glucose is a fermentable carbohydrate. Potassium di-hydrogen phosphate is a buffering agent and magnesium sulfate is a source of divalent ions and sulfate. In order to curtail the size of the colony diameters of spreading fungi, the antifungal agent dichloran is added to the base and the pH is reduced to 5.6. Rose Bengal suppresses growth of bacteria and restricts the size and height of colonies of more rapidly growing molds. The inclusion of chloramphenicol ensures the suppression of bacteria present in environmental and food samples. Rose Bengal is absorbed by yeast and mold colonies and this further aids in their enumeration. Occasionally reduced recovery of yeasts may be encountered due to the increased activity of Rose Bengal at pH 5.6.
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DNase agar is used primarily in clinical laboratories to differentiate pathogenic Staphylococcus aureus from other staphylococci based on deoxyribonuclease (DNase) activity. The tryptone provides the required carbon, nitrogen and vitamins. Sodium chloride maintains the osmotic balance. The addition of DNA to the base medium provides a simple method to check for DNase activity. Following incubation of the inoculated medium, the surface of the medium is flooded with a small quantity of 1M hydrochloric acid to precipitate the DNA. This results in the medium turning opaque. Organisms that can produce sufficient quantity of a DNase enzyme will hydrolyse the DNA resulting in a clear area around the colonies. Whereas DNase negative organisms will not produce clearing. NB: As with most tests of this type a positive result should not be taken in isolation and other appropriate tests, e.g. coagulase test, latex agglutination etc., should be carried out.
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DNase agar is used primarily in clinical laboratories to differentiate pathogenic Staphylococcus aureus from other staphylococci based on deoxyribonuclease (DNase) activity. The tryptone provides the required carbon, nitrogen and vitamins. Sodium chloride maintains the osmotic balance. The addition of DNA to the base medium provides a simple method to check for DNase activity. The methyl green fades into a colourless compound if the DNA in the medium is depolymerised. Organisms that can produce sufficient quantity of a DNase enzyme will hydrolyse the DNA resulting in a clear area around the colonies. Whereas DNase negative organisms will not produce clearing. NB: As with most tests of this type a positive result should not be taken in isolation and other appropriate tests, e.g. coagulase test, latex agglutination etc., should be carried out.
