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CLED SI Agar Cystine Lactose Electrolyte Deficient Single Indicator (CLED SI) Agar is based on Mackey and Sandys formulation and is popular for culturing urine specimens in the clinical laboratory. The reduced number of electrolyte level prevents swarming of Proteus spp. The peptone and beef extract is the source of the required nitrogen, carbon and vitamins. Lactose is a carbohydrate. The inclusion of bromothymol blue as a pH indicator allows easy differentiation of lactose and non-lactose fermenting organisms. L-Cystine is also present to benefit those organisms that have a particular cystine requirement. -
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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Columbia agar is a general-purpose, non-selective medium capable of supporting the growth of most micro-organisms based on the original Columbia agar formulation described by Ellner et al. from Columbia University. With further enrichment using blood, most fastidious organisms can be isolated and their β-haemolytic reactions can be determined in order to aid identification. The peptone is the source of the required nitrogen, carbon and vitamins. Starch increases growth of Neisseria spp., and enhances the haemolytic reactions of some streptococci. This medium is relatively free of reducing sugars, which have been reported to adversely influence the haemolytic reactions of β-haemolytic streptococci . Supplementation of the base medium with blood (5- 10%) will provide additional growth factors for fastidious microorganisms, and aids in determining haemolytic reactions. It should be noted that the haemolytic patterns of isolates may vary with the source of animal blood and the type of basal medium used. 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 medium is intended for the cultivation and enumeration (via the Miles and Misra technique) of Lactobacillus spp. from a variety of sources and can be used in conjunction with MRS Agar (KM0080). This medium is a modification on the formulation developed by de Man, Rogosa and Sharpe.(1) The peptones, beef extract, yeast extract provides the required carbon, nitrogen and vitamins in this medium. Glucose is a fermentable carbohydrate. 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 magnesium sulphate, manganese sulphate and polysorbate 80 act as growth stimulants. The medium can be made more specific for lactobacilli generally by lowering the pH to between 5.0 and 5.5. This has the effect of inhibiting most streptococci that may otherwise grow on the medium and can be readily confused with lactobacilli.
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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 desoxycholate 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.
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Edwardsiella ictaluri medium is a selective medium for the isolation of Edwardsiella spp. based on the formulation by Shotts et al. (1) Edwardsiella spp. may be differentiated from other microorganisms on this medium due to its colony morphology. The peptones provide the required carbon, nitrogen and vitamins. Sodium chloride maintains the osmotic balance. Colistin and bile salts are selective agents to inhibit most Gram-negative and Gram- positive organisms. Mannitol is a fermentable carbohydrate and bromthymol blue is a pH indicator. Phenylalanine and ferric citrate are used to detect phenylalanine deaminase activity in Proteus spp. Agar is a solidifying agent. Shotts et al. (1) noted Proteus spp. swarming can overgrow on a mixed cultured sample. Therefore, a selective supplement (LS0021) may be added to the medium to restrict Proteus spp. swarming
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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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Eosin Methylene Blue agar (EMB) is a selective medium primarily for the isolation of coliforms from clinical, food and environmental samples. This is the modified formulation of EMB proposed by Levine with a higher concentration of lactose and the sucrose omitted. The peptone provides the required carbon, nitrogen and vitamins. Lactose is a fermentable carbohydrate and di-potassium phosphate is a buffer. Eosin Y and methylene blue are indicators. Methylene blue is also a selective agent. During strong acidic conditions, the dyes impart a metallic sheen to certain lactose fermenters, such as Escherichia coli.
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Fastidious Anaerobe Agar is intended as a primary isolation medium capable of supporting most clinically significant anaerobes. The formulation is complex and includes detoxification agents (starch and sodium bicarbonate), growth enhancing agents (L-Cysteine, arginine, vitamin K, sodium succinate, glucose and pyrophosphate), as well as haemin to encourage pigment production in Bacteroides melaninogenicus. The peptone is the source of the required nitrogen, carbon and vitamins. Glucose also acts as a carbon source and sodium pyruvate as an energy source. Sodium chloride maintains the osmotic balance in the medium. Sodium pyrophosphate acts as a buffering agent and sodium succinate improves the growth of organisms such Bacteroides spp. Supplementation of the base medium with blood (5 - 10%) will provide additional growth factors for the more fastidious microorganisms, and aids in determining any haemolytic reactions. 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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GC Agar when used with blood and other enrichment is for the isolation of Neisseria gonorrhoeae but is also capable of supporting the growth of most fastidious micro-organisms. This medium is based on the modified formulation described by Thayer and Martin that was based on the original formulation stated by Johnson. Enrichment is usually attained using lysed blood but haemoglobin powder or chocolated blood are suitable alternatives. Additional enrichment can be provided by the addition of Suplex supplement (BM0478) which consists of yeast extract and glucose. Selective variants of GC Agar can be prepared through the addition of various selective supplements such as VCAT (LS0002) or LCAT (LS0001). These supplements will suppress most of the background flora likely to be present in specimen and will restrict the swarming of Proteus spp. The peptone is the source of the required nitrogen, carbon and vitamins. Sodium chloride maintains the osmotic balance in the medium. Starch is present to absorb toxic metabolites and phosphate buffers prevent pH changes during incubation. Related Supplements : BM0478 Suplex, LS0001 GC LCAT Selective Supplement, LS0002 GC VCAT Selective Supplement
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Hektoen enteric agar was developed by King and Metzger as a differential selective medium for the isolation of Shigella spp. and Salmonella spp. species from enteric pathological samples. The meat peptone and yeast extract provide the required nitrogen, carbon and vitamins. Lactose, sucrose and salicin are fermentable carbohydrates. Bromothymol blue is added as a pH indicator in order to identify carbohydrate fermenting organisms. The combination of ferric ammonium citrate and sodium thiosulfate allows the production of hydrogen sulphide. Hydrogen sulphide positive colonies produce black centred colonies. Sodium chloride maintains the osmotic balance. The bile salts and acid fuchsin inhibit Gram-positive organisms.
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This is a selective medium for the isolation of Helicobacter pylori from clinical samples. The medium is based on a modification of Campylobacter CCDA Blood Free Medium with charcoal, ferrous sulphate and sodium pyruvate replacing the horse blood. The medium is made selective by the addition of vancomycin and cefsulodin, to suppress other bacteria, and amphoteracin to inhibit yeasts. Horse serum (10%) is also added to promote optimum growth of Helicobacter spp. Related Supplements : LS0031 Helicobacter pylori Selective Supplement, SHS500 Sterile Horse Serum 500ml
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Hoyles agar is selective culture medium for the isolation and differentiation of Corynebacterium diphtheriae types. Hoyles agar allows for rapid growth of the organisms and normally 18 hours incubation should be sufficient for a diagnosis. As the medium is highly selective, inoculation should be by rubbing the swab (or other material) over the entire surface of the agar, there is no need to spread the inoculum with a loop indeed doing so can cause the organism to be missed especially when they are present only in small numbers. The Elek method can be used to determine the toxigenicity of any C. diptheriae strains. The beef extract and peptone act as a source of nitrogen, carbon and vitamins. The sodium chloride maintains osmotic balance. This medium should be used in conjunction with two supplements: lysed horse blood at 50 ml/l and 10ml/l of potassium tellurite 3.5% solution (BM2230). Lysed horse blood provides added nutrients to the medium and potassium tellurite inhibits Gram-negative and several Gram-positive microorganisms. Related Supplements : BM2290 3.5% Potassium Tellurite Solution, Horse Blood Lysed
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Kligler iron agar is used to differentiate between some of the enterobacteriacae on the basis of three reactions: fermentation of lactose and glucose and the production of hydrogen sulphide. Kligler iron agar is a modification of the original formulation developed by Kligler. It incorporates the principles of Russell’s double sugar agar with Kligler ‘s lead acetate agar. The peptone provides the required nitrogen, carbon and vitamins. Lactose 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 the osmotic balance.
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Thiosulphate citrate bile salts sucrose (TCBS) agar is a selective medium used in microbiology laboratories to isolate Vibrio spp. The formulation was developed by Kobayashi et al. which was modified from Nakanishi’s formulation. The yeast extract and peptone are the source of the required nitrogen, carbon and vitamins. TCBS agar contains high concentrations of sodium thiosulphate, sodium citrate and ox bile to inhibit the growth of Gram-positive organisms and suppress coliforms. Sucrose is included as a fermentable carbohydrate for the metabolism of Vibrio spp. Sodium chloride maintains the osmotic balance in the medium. Sodium thiosulphate also serves as a sulphur source and, in combination with ferric citrate, detects hydrogen sulphide production. Thymol blue and bromothymol blue are included as indicators of pH changes.
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Lactalbumin hydrolysate is obtained through enzymatic hydrolysis of lactalbumin protein in milk whey. This product is rich in essential amino acids as well as providing a source of nitrogen, carbon and vitamins. It is commonly utilized in media for tissue culture and for the production of vaccines as well as being useful for bacterial and fermentation media.
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Lactose broth is used for the performance and confirmation of the Presumptive Test for coliforms in water and dairy samples. This medium is also frequently used as a pre-enrichment medium when testing foods, water samples and dairy products for Salmonella spp. Beef extract and gelatin peptone provide the required carbon, nitrogen and vitamins in this medium. Lactose is a fermentable carbohydrate. Fermentation of lactose is detected by the production of gas
