Aerobically at 37°C for 16-24 hours

//Aerobically at 37°C for 16-24 hours
  • Bile Aesculin Medium is generally used for the differentiation and presumptive identification of Group D streptococci (enterococci). Enterococci hydrolyse aesculin forming, amongst other products, aesculetin which in turn combines with Ferric ammonium citrate producing a dark brown or black complex. The presence of Bile salts in the medium inhibits gram positive organisms other than enterococci. The medium can also be used for the presumptive identification of certain organisms within the Enterobacteriaceae group such as Klebsiella spp., Enterobacter spp., etc.
  • This is a very nutritious general-purpose medium suitable for the isolation of most organisms including many fastidious anaerobes. It is particularly recommended for streptococci and neisseria.
  • A very nutritious isotonic general-purpose medium with a low concentration of Glucose to stimulate early growth, Brain Heart Infusion Broth is suitable for the isolation of most micro-organisms including many fastidious organisms and, with enrichment as appropriate, is suitable as a base for blood culture medium. A phosphate buffer is incorporated to help neutralise any acids produced as a result of Glucose utilisation and thus maintain viability of the organisms. This particular formulation also has added Glycerol to act as cryopreservative if the medium is used for the long term frozen storage of microorganisms. NB: Organisms that produce large amounts of acid in the medium may overwhelm the buffering system and as a result ‘auto-sterilise’ the culture.
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    CLED Agar

    CLED Agar Mackey and Sandy’s formulation this medium is popular for Urine Culture in the clinical laboratory. The lack of electrolytes inhibits the spreading of Proteus spp. and Bromothymol Blue indicator allows easy differentiation of Lactose and Non-Lactose fermenting organisms. 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.
  • CLED Agar (Bevis) A modification by Bevis of the original CLED medium of Mackey & Sandys. This formulation uses a double indicator system (Andrade’s (Acid fuchsin) and Bromothymol blue) to improve differentiation of Lactose and Non-lactose fermenting organisms. The lack of Sodium Chloride also prevents the swarming of Proteus spp.
  • Colorex™Acinetobacter MDR is a chromogenic medium for the detection of multi-drug resistant (MDR) Acinetobacter spp. Positive colonies exhibit a distinct red colouration with a pale grey centre enabling easy interpretation amongst blue, violet or colourless colonies that may be produced by other Gram –ve bacteria. Gram +ve bacteria and yeast are inhibited on this medium. Limitations: 1.  Some Pseudomonas, Stenotrophomonas and Burkholderia spp. may form pale red colonies on this medium but are readily distinguishable due to differences in colonial morphology compared to the Acinetobacter spp. An oxidase test will readily differentiate any Pseudomonas spp. 2. Some Enterobacteriaceae isolates may form blue colonies on this medium. 3. Definitive MDR characterisation may require additional antibiotic susceptibility testing.
  • Colorex™ MRSA is a chromogenic medium for the selective isolation of Methicillin-Resistant Staphylococcus aureus (MRSA). The medium can be used for the routine screening of clinical specimens for MRSA from a variety of sampling sites such as the nose, throat and groin. The medium incorporates a nutritious peptone base medium and a number of selective agents to inhibit most Gram-negative and Gram-positive bacteria as well as yeasts and moulds. The chromogenic detection of specific enzyme activity leads to the formation of pink/mauve colonies indicating MRSA (including low level resistant and hetero-resistant strains) following incubation at 37°C for 18-24 hours. Other organisms, if present are indicated by blue or colourless colonies. Any presumptive isolates must be confirmed using serological and/or biochemical techniques available to the laboratory. The use of this chromogenic medium does not diminish the requirement for conventional antimicrobial susceptibility tests for the confirmation of methicillin resistance. Limitations: 1. S.aureus strains that possess a low MIC to the selective agent present in the medium but are mec A negative may form colonies on the medium. 2. Some MRSA strains may form typical colonies surrounded by a matte halo. The formation of the halo serves no diagnostic function. 3. Certain methicillin-resistant coagulase-negative staphylococci (CNS) may produce characteristic colonies. In some cases differentiation may be achieved by examination of the colour of these colonies, as they may be considerably darker in colour (bluish purple to a very dark pink/magenta). 4. Certain bacterial species other than staphylococci may produce colonies with a characteristic colour.
  • Colorex™ MRSA is a chromogenic medium for the selective isolation of Methicillin-Resistant Staphylococcus aureus (MRSA). The medium can be used for the routine screening of clinical specimens for MRSA from a variety of sampling sites such as the nose, throat and groin. The medium incorporates a nutritious peptone base medium and a number of selective agents to inhibit most Gram-negative and Gram-positive bacteria as well as yeasts and moulds. The chromogenic detection of specific enzyme activity leads to the formation of pink/mauve colonies indicating MRSA (including low level resistant and hetero-resistant strains) following incubation at 37°C for 18-24 hours. Other organisms, if present are indicated by blue or colourless colonies. Any presumptive isolates must be confirmed using serological and/or biochemical techniques available to the laboratory. The use of this chromogenic medium does not diminish the requirement for conventional antimicrobial susceptibility tests for the confirmation of methicillin resistance. Limitations: 1.  S.aureus strains that possess a low MIC to the selective agent present in the medium but are mec A negative may form colonies on the medium. 2. Some MRSA strains may form typical colonies surrounded by a matte halo. The formation of the halo serves no diagnostic function. 3. Certain methicillin-resistant coagulase-negative staphylococci (CNS) may produce characteristic colonies. In some cases differentiation may be achieved by examination of the colour of these colonies, as they may be considerably darker in colour (bluish purple to a very dark pink/magenta). 4. Certain bacterial species other than staphylococci may produce colonies with a characteristic colour.
  • Colorex™ Salmonella Plus is a chromogenic media for the isolation and presumptive identification of Salmonella spp, S typhi, S.paratyphi and lactose positive Salmonella from foodstuffs. Any presumptive Salmonella spp. will produce a mauve colouration; other organisms will be blue or colourless in appearance. Cefsulodin is added as a selective agent to inhibit the growth of Pseudomonas and Aeromonas species. Any presumptive isolates must be confirmed using serological and biochemical techniques available to the laboratory. This product meets the requirements of ISO 6579:2002 standard.
  • This is a chromogenic medium for the isolation and presumptive identification of Staphylococcus aureus. Mauve colonies indicate Staph aureus following incubation (18 – 24 hours) at 37°C, other organisms, if not inhibited, are indicated by blue or colourless colonies. Studies have suggested that this media has a specificity and sensitivity of 99.4% and 95.5% respectively (Gaillot et al 2000).
  • About a quarter of pregnant women in the UK are estimated to carry Streptococcus agalactiae. As a result of this, babies become colonized with Streptococcus agalactiae (GBS) during labour and birth; the vast majority are unaffected by this colonization, however, a small percentage become infected with conditions such as eye infections, pneumonia, septicaemia or meningitis. Colorex™ StrepB Agar is a chromogenic media that presumptively identifies Streptococcus agalactiae (mauve/red colonies) after 18-24 hours incubation in aerobic conditions. Enterococci are differentiated by the formation of blue colonies; other organisms are inhibited or colourless. NB: Some strains of Group A, C & G streptococci may also produce mauve colonies. Therefore, final identification may require additional testing.
  • Vancomycin-resistant Enterococcus (VRE) infections are especially aggressive and have been associated with mortality rates approaching 60% to 70%. They are now the second-leading cause of nosocomial infections in the U.S., and their prevalence is increasing worldwide. Resistance to vancomycin has the potential to be transferred from bacteria to bacteria. Cross-resistance is mediated by plasmids and transposons, which may transfer the genes associated with resistance to other much more aggressive pathogens, such as staphylococci and streptococci. Three principal types of vancomycin resistance are found in Enterococcus spp.; VanA, VanB and VanC genotypes. VanA and VanB types account for most significant infections in clinical settings, involving E.faecium and E.faecalis. VanC resistance is a low-level intrinsic resistance found in other Enterococcus spp. The Colorex™ VRE media is another chromogenic media in the Colorex™ range, enabling presumptive identification of vancomycin resistant Enterococci by the formation of mauve/pink coloured colonies (for VanA and VanB genotypes) and blue coloured colonies (for VanC genotypes) after 18-24 hours incubation.
  • A basic general-purpose blood free medium, capable of supporting the growth of most micro-organisms, including many fastidious organisms that do not require blood.
  • Columbia Agar Base with 5% Horse Blood & Streptococcal Selective Supplement This is a medium for the selective isolation of Streptococcus spp. from clinical samples. Based on Columbia Agar Base enriched with 5% Horse Blood it is made selective by the addition of Colistin and Oxolinic Acid.
  • This is a medium for the selective isolation of Staphylococcus spp. and Streptococcus spp. primarily from clinical specimens. Based on Columbia Agar Base enriched with 7% Horse Blood the medium is made selective by the inclusion of Colistin and Nalidixic Acid to suppress the growth of the majority of Gram negative bacteria.
  • This is a selective medium for the isolation of Staphylococcus and Streptococcus spp. Based on Columbia Agar, it is enriched by the addition of Sheep Blood (7%) the medium is also made selective by the inclusion of Colistin and Naladixic Acid to suppress the growth of the majority of Gram negative bacteria. The addition of sheep blood the medium allows for good colonial appearance, pigment production and excellent haemolysis from beta-haemolytic streptococci.
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    DNase Agar

    DN'ase Medium DNase Agar is used primarily in clinical laboratories to differentiate Staphylococcus aureus from other Staphylococci based on deoxyribonuclease activity. Following incubation of the plate and confirmation of a pure growth of Staphylococci, the surface of the medium is covered with a small quantity of 1M Hydrochloric Acid to precipitate the DNA. Staphylococcus aureus produce DNase enzymes that hydrolyse DNA resulting in a clear area around the colonies, described as being DNase positive, whereas coagulase negative Staphylococci do 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 Staphylococcus aureus from other staphylococci based on deoxyribonuclease activity. Staphylococcus aureus produce DNase enzymes that hydrolyse DNA resulting in a colourless zone around the colonies, described as being DNase positive, whereas coagulase negative staphylococci do not produce clearing. This particular formulation can also be used for Streptococci and Serratia. 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.
  • Edwards Medium (Modified) with 7% Sheep Blood This is a medium for the selective isolation of streptococci, particularly Streptococcus agalactiae, involved in bovine mastitis. The medium is enriched by the addition of 7% Sheep Blood and made selective by the inclusion of Crystal Violet and Thallous Sulphate. Aesculin is also present and assists in the differentiation of Streptococcus agalactiae, which give rise to blue colonies, from Aesculin positive Group D streptococci which produce black colonies.
  • A medium for the selective isolation of group B streptococci. This information has been obtained directly from the HPA files at the customers request.
  • LB media formulations have been an industry standard for the cultivation of Escherichia coli as far back as the 1950s. These media have been widely used in molecular microbiology applications for the preparation of plasmid DNA and recombinant proteins. Vitamins and certain trace elements are provided by yeast extract. Sodium ions for transport and osmotic balance are provided by sodium chloride. Tryptone is used to provide essential amino acids to the growing bacteria.
  • LB media formulations have been an industry standard for the cultivation of Escherichia coli as far back as the 1950s.These media have been widely used in molecular microbiology applications for the preparation of plasmid DNA and recombinant proteins. This media has the addition of Kanamycin at 0.05gms/L for use with Kanamycin resistant strains and cells harbouring selection plasmids containing the Kanamycin resistance gene.Peptides and peptones are provided by tryptone. Vitamins and certain trace elements are provided by yeast extract. Sodium ions for transport and osmotic balance are provided by sodium chloride. Tryptone is used to provide essential amino acids to the growing bacteria, while the yeast extract is used to provide a plethora of organic compounds helpful for bacterial growth.
  • 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. It has the disadvantage that many strains of Proteus spp will spread on it and for this reason MacConkey Agar without Salt may be preferred.
  • This is a selective medium primarily for the isolation of Enterobacteriacae from waters & 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 micrococci.
  • Originally introduced for the isolation and differentiation of Lactose & Non-Lactose Fermenting enteric organisms the medium in this case has been modified to improve the isolation of staphylococci and enterococci. The absence of Sodium Chloride provides a low electrolyte medium that prevents spreading of most Proteus spp. Although recommended for use in the examination of urine samples in clinical laboratories it has uses in Food, Water and Dairy applications.
  • Approved by the Clinical & Laboratory Standards Institute (CLSI formerly known as the NCCLS) in USA this medium can be considered as an alternative to Iso-Sensitest Broth for antimicrobial sensitivity testing and MIC determinations by tube dilution methods. It is low in Thymine and Thymidine and is therefore suitable for use in testing Sulphonamides & Trimethoprim. It is sometimes used in conjunction with Mueller-Hinton Agar.
  • Pages Amoeba Saline & Agar No.1 This is a non-nutrient medium based on Page’s Amoeba Saline, a buffered salt solution, solidified with 1.5% Agar.
  • A general-purpose medium for the cultivation of organisms that are less fastidious in their nutritional requirements.
  • Based on Nutrient Broth with an additional 6.0% Sodium Chloride (Total Sodium Chloride content = 6.5%) this medium is suitable for use in the investigation of outbreaks involving Staphylococcus aureus including MRSA. The additional Sodium Chloride inhibits most other organisms allowing the staphylococci to multiply freely even if present in small numbers. The medium is generally used as an enrichment medium in conjunction with subculture onto selective solid media.
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    Peptone Water

    A general-purpose medium that can be used as a base for carbohydrate fermentation media. It has a high level of Tryptone and is therefore also suitable for use in Indole testing.
  • This is one of the large group of media, affectionately known as ‘Peptone Water Sugars’, that are generally used in the screening and/or identification of organisms particularly the enterobacteriacae. A positive fermentation of the substrate is clearly indicated by the medium turning pink due to the inclusion Andrade’s Indicator.
  • Sorbitol MacConkey with Cefixime & Tellurite (CT-Smac) This is a selective differential medium for the isolation of Escherichia coli 0157:H7. It differs from other MacConkey medium 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. The medium is made more selective by the addition of the antimicrobial Cefixime and Potassium Tellurite.
  • Thiosulphate Citrate Bile Salts Sucrose (TCBS) Agar TCBS is a selective isolation medium for culture of pathogenic Vibrio spp. from clinical samples. The formulation was developed by Kobayashi, Enomoto, Skazaki and Kuwahara. This medium inhibits most enterobacteriacae for at least 24 hours. For the isolation of Vibrio spp. other than V.cholerae in environmental bacteriology, it is advisable to incubate at the lower temperature range of 20°C – 30°C. NB - It is not recommended to perform an oxidase test on any presumptive positive isolates directly from TCBS medium.
  • Triphenyltetrazolium Chloride Soya Tryptone (TSAT) Agar Complete Triphenyltetrazolium Chloride (TTC) has been added as an indicator to various media, and recommended by several workers as being helpful in the early recognition and identification of a variety of bacteria including Escherichia coli, Vibrio parahaemolyticus and enterococci. This particular formulation is based on a Tryptone Soya Agar with added Sucrose and is particularly useful when performing counts on food and food product samples. Many of the enterobacteriaceae and enterococci will reduce the TTC to a formazan which colours the colonies deep red making them easier to distinguish and identify. The presence of the Sucrose can also assist in the differentiation of Sucrose fermenting and non-fermenting strains.
  • Tryptone Soya Broth (Modified) with Novobiocin (20mg/L) This is a selective enrichment broth for the isolation of Escherichia coli 0157, primarily from food and food products, and is capable of detecting the organisms even when they are present in small numbers. It is also increasingly being used in clinical laboratories when screening faecal samples. Based on Tryptone Soya Broth it is made selective for Escherichia coli 0157 by the addition of bile salts and Novobiocin and is also buffered to maintain the pH during incubation. This medium is generally used in conjunction with selective agar subculture (e.g. Sorbitol MacConkey Agar with Cefixime Tellurite – (CT-SMAC)).
  • Tryptone Water is an alternative medium to Peptone Water and more reliable for the testing of Indole production. The medium has a high content of Tryptophan that many organisms, particularly coliforms, break down to form Indole. After incubation add a few drops of Indole reagent to determine the Indole reaction  (Red colour is Positive).
  • A medium for the enumeration of coliform organisms in food and dairy products. Lactose fermenters produce red/purple colonies often surrounded by a halo of the same colour. Non-lactose fermenters produce pale colonies. Selective agents are Bile salts and crystal violet used to inhibit Gram positive and non-enteric organisms.
  • A modification of Violet Red Bile agar designed to give a ‘coliform’ count. In this medium lactose is substituted with glucose. Glucose is fermented by all members of the Enterobacteriaceae thus V.R.B.G.A gives a presumptive Enterobacteriaceae count. Bile salts and crystal violet are used to inhibit Gram positive and non-enteric organisms. The growth of non-fermentative Gram negative bacteria can be suppressed by using the agar overlay method.
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    XLD Agar

    Originally introduced as an aid to recovery of Shigella spp. XLD is also a first class medium for recovery of Salmonella spp. It differs from other media of this type in that it has less Sodium Desoxycholate as its selective agent. The indicator system is somewhat complex taking advantage of the fermentation or otherwise of three carbohydrates (Lactose Sucrose and Xylose) together with Lysine Decarboxylase and Sodium Thiosulphate as an indication of the presence or absence of Hydrogen Sulphide.
  • Xylose Lysine Deoxycholate (XLD) agar is used for the isolation and detection of Salmonella and Shigella spp. Developed by Taylor, xylose lysine agar base was used for isolating and differentiating Gram-negative enteric bacilli. The addition of sodium thiosulfate, ferric ammonium citrate, and sodium deoxycholate created the more selective medium, XLD agar. This medium was found to be satisfactory for the isolation of Shigella and Providencia spp., as well as proving to be an effective differential media. The yeast extract is the source of the required nitrogen, carbon and vitamins. Lactose, sucrose and xylose are fermentable carbohydrates. Sodium deoxycholate, sodium thiosulphate and ferric ammonium citrate are selective agents. Phenol red acts as a pH indicator. Sodium chloride maintains the osmotic balance. Most enteric bacteria including Salmonella spp., can ferment xylose to produce acid. Shigella spp. are unable to do this and thus the colonies remain red. Once xylose has been completely utilized Salmonella spp. will decarboxylate lysine resulting in a pH increase to alkaline. Salmonella and Shigella spp. are differentiated as Salmonellae spp. are able to metabolise thiosulphate producing hydrogen sulphide resulting in colonies with black centres. Stool specimens or rectal swabs may be plated directly onto XLD agar. Selective enrichment broths, such as Selenite Broth or Tetrathionate Broth, may be used prior to streaking. For specific procedures refer to appropriate references.