Firm Gel

//Firm Gel
  • 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).
  • 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
  • Blood agar base No. 2 is a general-purpose medium 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. Haemolysis observations may vary with the type of blood being used. Previous studies have shown that sheep blood provides the most reliable colony and haemolysis characteristics. The peptone, yeast extract and liver digest act as nitrogen, carbon and vitamin sources in this medium. Sodium chloride maintains osmotic balance. Related Supplements : Defibrinated Sheep Blood, Defibrinated Horse Blood, LS0008 Staph/Strep Selective Supplement, LS0017 Neomycin Selective Supplement
  • 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.
  • Brilliant green agar is for the selective isolation of Salmonella spp., other than S. typhi. Brilliant green agar was first cited by Kristensen et al. in 1925 but was subsequently modified by the Netherlands Institute for Public Health. Brilliant green agar is generally used in conjunction with XLD agar (KM0013) as a secondary plating medium for subculture from selective enrichment media in food and environmental testing. It should be noted that the medium is highly selective and therefore not suited to the isolation of Salmonella spp. from samples where the numbers may be low. Beef extract, peptone and yeast extract provide the required carbon, nitrogen and vitamins. Di-sodium hydrogen phosphate and sodium di-hydrogen phosphate are buffering agents. Lactose and sucrose are fermentable carbohydrates. Phenol red is a pH indicator and turns the medium yellow during lactose and/or sucrose fermentation. Brilliant green inhibits Gram-positive bacteria and Gram-negative bacilli other than Salmonella spp. NB: It is not recommended that this medium be used for the isolation of Salmonella typhi or Shigella spp. Related Supplements : LS0024 Novobiocin Supplement (20mgs/L)
  • 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.
  • 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
  • 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
  • Campylobacter Blood-Free Selective Medium (CCDA) is one of several media formulations available for the selective isolation of Campylobacter spp., primarily C. jejuni and C. coli. CCDA was described by Bolton et al. and formulated to replace blood with a combination of charcoal, ferrous sulphate, and sodium pyruvate. CCDA is recommended for food testing. CCDA with the addition of yeast extract and cefoperazone is used in the isolation of Campylobacter spp. from foodstuffs and swabs in the FDA/BAM method. This product complies with the requirements of ISO 10272-1:2006. 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). The meat peptone, beef extract and tryptone provide the required nitrogen, carbon and vitamins. Bacteriological charcoal absorbs toxic compounds and metabolites. Ferrous sulphate and sodium pyruvate are oxygen scavengers. Sodium desoxycholate is a selective agent. Through the addition of campylobacter (Preston) supplement (LS0010), which consists of cefoperazone and amphotericin B, enteric flora is suppressed. Related Supplements : LS0010 Campylobacter (Preston) Selective Supplement
  • KM0052

    CEMO Agar

    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.
  • 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 :
  • KM0185

    Charcoal Agar

    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
  • 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.
  • KM0005

    CLED DI Agar

    Bevis modified Mackey and Sandy’s original medium by introducing a double indicator to improve the differentiation of lactose and non-lactose fermenting coliforms, staphylococci and streptococci spp. Cystine Lactose Electrolyte Deficient Double Indicator (CLED DI) is popular for urine culture in the clinical laboratory. The reduced number of electrolytes 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 and Andrade’s as indicators 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. Streptococcus pyogenes and many other fastidious organisms that do not require the presence of blood can grow on this medium.  
  • KM0004

    CLED SI Agar

    CLED SI Agar Cystine Lactose Electrolyte Deficient Single Indicator (CLED SI) Agar is based on Mackey and Sandy’s 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).
  • KM0001

    Columbia Agar

    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 SupplementLS0012 Bacitracin Selective Supplement, LS0011 Campylobacter Growth Supplement, LS0009 Campylobacter (Skirrow) Selective Supplement
  • 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.  
  • 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.
  • 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
  • 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.
  • KM0053

    DNase Agar

    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.  
  • 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.  
  • 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
  • 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.  
  • 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
  • KM0016

    GC Agar

    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
  • 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.
  • 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
  • Hoyle’s agar is selective culture medium for the isolation and differentiation of Corynebacterium diphtheriae types. Hoyle’s 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
  • 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.
  • 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.
  • LB agar (Lennox) is used for the cultivation and maintenance of recombinant strains of Escherichia coli and is based on the formulation stated by Lennox. This medium is typically used in molecular biology procedures such as the detection of phage or plasmid transformed bacteria. LB agar (Lennox) is prepared using 5 g/L of sodium chloride and this level varies from that described by Miller. This allows for additional sodium chloride to be added at the point of preparation if required. Enzymatic digest of casein provides the required nitrogen and carbon for organism growth. Vitamin B complex required by recombinant strains of E. coli are supplied by the yeast extract. Sodium chloride maintains the osmotic balance and provides sodium ions for membrane transport. Related Supplements : LS0035 Ampicillin Selective Supplement, LS0037 Kanamycin Selective Supplement
  • Luria Bertani (LB) agar (Miller) is used for the cultivation and maintenance of recombinant strains of Escherichia coli and is based on the formulation stated by Miller. This medium is typically used in molecular biology procedures such as the detection of phage or plasmid transformed bacteria. LB agar (Miller) is prepared using 10 g/L of sodium chloride and this level varies from that described by Lennox. Enzymatic digest of casein provides the required nitrogen and carbon for organism growth. Vitamin B complex required by recombinant strains of E. coli are supplied by the yeast extract. Sodium chloride maintains the osmotic balance and provides sodium ions for membrane transport. Related Supplements : LS0035 Ampicillin Selective Supplement, LS0037 Kanamycin Selective Supplement
  • Legionella agar was designed for the isolation of Legionella spp. and is used primarily in water and environmental laboratories. Since Legionella spp. are fastidious organisms, the medium contains yeast extract as a source of nitrogen, carbon and vitamins. Charcoal is also included to neutralise growth-inhibiting substances and agar is the solidifying agent. The medium requires supplementation with ferric pyrophosphate as a source of iron, L-cysteine, an essential amino acid for the growth of Legionella spp. and α-ketoglutaric acid, which acts as a growth stimulant. ACES buffer/potassium hydroxide is also added to maintain the optimal pH of 6.9 for growth of Legionella spp. Omission of the L-cysteine produces a confirmation medium that can be used to test presumptive Legionella spp. as isolates will not be able to grow. Selective versions of the medium can also be created by the addition of various selective agents. GVPC is the most popular for water testing and BMPA for clinical testing. Related Supplements : LS7044 Legionella BCYE Supplement, LS7045 BCYE without Cysteine
  • 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.
  • 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
  • Long and Hammer agar is for the detection of aerobic microorganisms in fish and fish products. This media is recommended for the determination of spoilage organisms in fresh and lightly preserved seafoods. (1) The proteose peptone acts as a nitrogen, carbon and vitamin source. Gelatine is a protein source and solidifying agent. Sodium chloride maintains the osmotic balance and di-potassium hydrogen phosphate is a buffer. 1) Nordic Committee on Food Analysis. (2006) Aerobic count and specific spoilage organisms in fish and fish products. NMKL Method No 184
  • 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.  
  • MacConkey agar No. 3 is a selective medium primarily for the isolation of Enterobacteriacae from waters and sewage. This media differs from the original MacConkey formulation in that as well as bile salts, crystal violet has been included as an additional selective agent. This has the effect of inhibiting Gram-positive organisms. The peptone acts as a nitrogen, carbon and vitamin source. Sodium chloride maintains osmotic balance. Lactose is a carbohydrate and during its fermentation causes a confined pH drop around the bacterial colony. This causes a colour change in the pH indicator, neutral red and bile precipitation.  
  • This is a selective medium for the isolation and differentiation of bile tolerant Gram-negative (enteric) and Gram-positive (staphylococci and enterococci) organisms and has uses in all areas of bacteriology. This medium is recommended by the World Health Organisation and the Department of Health for the bacteriological examination of water. It has the disadvantage that many strains of Proteus spp. will spread on it and for this reason MacConkey Agar without salt and crystal violet may be preferred (KM0011).  
  • This medium was first introduced by MacConkey in 1905 for the isolation and differentiation of lactose and non-lactose fermenting enteric bacteria containing swarming strains of Proteus spp. MacConkey agar without salt and crystal violet is a differential medium that restricts swarming of Proteus spp. as sodium chloride is omitted from the medium to provide an electrolyte deficient medium. The omission of crystal violet permits the growth of Staphylococcus spp. and Enterococcus spp. The peptone is the nitrogen, carbon and vitamin source in this medium. Lactose is the fermentable carbohydrate. Lactose fermentation causes a local pH drop around the colonies which will react with the pH indicator, neutral red, and hence aids in differentiation. Bile salts act as the selective agent. Related Supplements : LS0189 Cefotaxime Supplement (1mg/L)
  • Malt extract agar is used for the detection, isolation and enumeration yeasts and moulds. The high carbohydrate content of the medium ensures rapid growth of yeasts and moulds. Malt extract and mycological peptone provide the carbon, protein and nutrient sources required by the organisms. The acidic nature of this medium allows for optimal growth of moulds and yeasts while restricting bacterial growth. Malt extract agar can also be used for the cultivation of fungi, although with the prolonged incubation necessary, cultures may become overgrown by bacteria. The selectivity of the medium can be increased by lowering the pH to 3.5-4.0 or by the addition of selective agents such as chloramphenicol. Related Supplements : LS0050 Chloramphenicol Selective Supplement
  • Mannitol Salt Agar is selective medium for the isolation of pathogenic staphylococci. The medium conforms to the requirements of the Harmonised USP/EP/JP. Chapman showed that adding a high level of sodium chloride to Phenol Red Mannitol Agar allowed for the recovery of pathogenic staphylococci. Pathogenic staphylococci produced yellow colonies whereas non-pathogenic staphylococci produced small red colonies. Pancreatic digest of casein, peptic digest of animal tissue and beef extract provide the required nitrogen, carbon and vitamins. The high level of sodium chloride inhibits most organisms other than staphylococci. Mannitol is a carbohydrate that is fermented by coagulase positive staphylococci. Phenol red is the pH indicator.
  • KM0062

    Marine Agar

    Marine agar is a medium used to support the growth of numerous marine bacteria. Originally formulation by ZoBell (1), its high saline levels are to simulate a close approximation of seawater which allows the marine bacteria to grow (2). The sodium chloride and marine minerals provide the high salinity needed for marine bacteria to thrive and aims to simulate sea water. The peptones provide the necessary nitrogen, amino acids and vitamins for growth. Agar is the solidifying agent. References (1) ZoBell, C.E. 1941. Studies on Marine Bacteria. I. The cultural requirements of heterotrophic aerobes. J. Mar. Res. 4, 42-75. (2) Lyman, J. and Fleming, R. H. 1940. Composition of Seawater. J. Mar. Res. 3, 134-146
  • Membrane Lauryl Sulphate Agar is used for the enumeration of Escherichia coli and other coliforms found in filter membranes used in water sample testing. The broth base, originally named Membrane Enriched Teepol broth,(1) was updated when Teepol 610 was removed from the formulation and replaced by sodium lauryl sulphate.(2&3) The peptones, yeast extract and lactose act as carbon, nitrogen and vitamin sources in this medium. The phenol red is added as a pH indicator to detect the fermentation of lactose to differentiate the coliforms. Sodium lauryl sulphate is an inhibitory agent. References (1) Burman, N. P., 1967. Development of membrane filter techniques. II. Adaptation to routine and special requirements. Proc. Soc. Wat. Treat. Exam., 16:40 (2) Joint Committee of PHLS and the Standing Committee of Analysis. 1980. J. Hyg. Camb., 85:181 (3) Stanfield, G. and Irving, T. E., 1981. A suitable replacement for Teepol 610 in the selective isolation of coliforms from marine waters and sewage. Water Research. 15:469-474
  • Mueller Hinton agar is used for antimicrobial susceptibility testing by the disk diffusion method as described by Bauer-Kirby. It has been approved as the definitive medium for this purpose by the European Committee on Anitmicrobial Susceptibility Testing (EUCAST). This formulation conforms to Clinical and Laboratory Standard Institute (CLSI). Beef extract and acid hydrolysate of casein provides the required nitrogen, carbon and vitamins in the medium. Starch absorbs any toxic metabolites produced. The medium contains low levels of thymidine and thymine and controlled levels of calcium and magnesium ions. The base medium can be supplemented with blood (5 – 10%). Nicotinamide adenine dinucleotide (NAD) may be added at 20 mg/L to make the medium suitable for use with more fastidious organisms such as Streptococcus pneumoniae and Haemophilus influenzae (LS0005). Related Supplements : LS0005 NAD Supplement (20mgs/L), Defibrinated Horse Blood
  • Mycological agar is a selective medium for the isolation of pathogenic fungi, particularly dermatophytes, from clinical specimens. Enzymatic digest of soybean meal provides the required carbon, nitrogen and vitamins. Glucose is an energy source for the metabolism of fungi. The addition of chloramphenicol further reduces the risk of bacterial contamination when processing material that may be heavily contaminated with coliforms. Cycloheximide should also be added (0.4g/L) to suppress the growth of commensal yeasts and saprophytic fungi.  
  • KM0141

    Nutrient Agar

    A basic general-purpose medium suitable for use in the cultivation of the less fastidious organisms particularly those that do not require the addition of blood or other enrichment. When used to prepare agar slopes or agar butts, the medium can be used to maintain control organisms. The peptone provides the required carbon, nitrogen and vitamins. Sodium chloride maintains osmotic balance.