Clinical / Veterinary

There are a number of media available for the selective isolation of Neisseria gonorrhoeae of which this is one. Based on the medium developed by Thayer & Martin, it includes Corn Starch to absorb toxic metabolites and is buffered to maintain a neutral pH. The medium is made selective by the inclusion of VCNT (Vancomycin, Colistin, Nystatin & Trimethoprim). Vancomycin and Colistin inhibit the growth of the majority of contaminating organisms likely to be present. Trimethoprim is included to reduce the spreading of Proteus spp and Nystatin to inhibit yeasts and fungi. Yeast Extract and Glucose are also added as further enrichment along with laked horse blood to ensure an more luxuriant growth of Neisseria gonorrhoeae.

Helicobacter Pylori Medium with 10% Horse Serum, Cefsulodin (10mg/L), Vancomycin (10mg/L) & Amphoteracin (20mg/L) 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 and is made selective by the addition of Vancomycin and Cefsulodin to suppress other bacteria and Amphoteracin to inhibit yeasts. 10% Horse Serum is also added to promote optimum growth of helicobacter.

A selective culture medium for the isolation and differentiation of Corynebacterium diphtheriae types, Hoyle’s medium 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.

Iso-Sensitest with 5% Horse Blood & NAD (20mg/L) (25ml per dish) This is a defined medium suitable for antimicrobial susceptibility testing and on which most organisms will grow. The medium has been enriched with Horse Blood to meet the demands of the more fastidious organisms and NAD (Nicotinamide Adenine Dinucleotide) is also included to further enhance the growth of Haemophilus spp. This medium is included in the recommendations of BSAC as being appropriate for the susceptibility testing of Haemophilus spp.

This is a selective medium for the isolation of Legionella spp used primarily in clinical and environmental laboratories. The base agar contains Yeast Extract as a source of protein, Charcoal to neutralise growth-inhibiting substances and is supplemented with Ferric Pyrophosphate as a source of iron, L-Cysteine hydrochloride and α-ketoglutarate to form amino acid and chelate respectively. ACES buffer and Potassium hydroxide are incorporated to maintain the optimal pH for growth. The medium is made selective by the addition of Cefamandole and Polymixin to inhibit most gram positive and gram negative organisms and Cyclohexamide is also included to inhibit yeasts and fungi.

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.

Middlebrooks 7H11 Selective Medium is an agar based medium for the isolation of Mycobacteria spp from clinical specimens. It differs from Middlebrooks 7H10 Agar in that it has a higher concentration of Malachite Green. The medium is complex and includes L-Glutamic Acid, Ammonium Sulphate, Sodium Citrate, Pyridoxine and Biotin as growth factors and Magnesium Sulphate, Ferric Ammonium Citrate as sources of trace ions. The medium is also made selective by the inclusion of Ticarcillin, Polymixin B, Trimethoprim and Amphotericin B. As with egg media Glycerol is included to enhance the growth of the Mycobacteria and Malachite Green is incorporated to provide a colour contrast between the colonies and the medium as well as contributing some inhibitory effect on organisms other than mycobacteria.

Approved by the National Committee for Clinical Laboratory Standards (NCCLS) in USA this medium is approved for use in antimicrobial sensitivity testing by the disc diffusion method and is recommended particularly for use with the Bauer-Kirby Technique It is low in Thymine and Thymidine and is therefore suitable for use in testing Sulphonamides & Trimethoprim and controlled to ensure correct zone sizes with Tetracyline and Aminoglycoside antibiotics. It can be considered as an alternative to Iso-Sensitest Agar. This particular formulation has an additional 2% Sodium Chloride added to the medium making it suitable for the detection of resistance to Methicillin in staphylococci and it is included in the recommendations of British Society for Antimicrobial Chemotherapy (BSAC) for this purpose. It is not however recommended for testing of organisms requiring a CO2 enriched environment due to the pH effect on the medium. If incubation in a CO2 enriched environment is essential control organisms should be included to confirm that results have not been altered.

Mueller-Hinton Agar is a defined medium used primarily in Antimicrobial Sensitivity Testing using the disc diffusion technique 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 medium contains low levels of thymidine and thymine and controlled levels of calcium and magnesium ions. Additional supplementation of the Mueller Hinton medium using 5% Horse Blood and 20mg/L of Nicotinamide adenine dinucleotide (NAD) makes it suitable for use with the more fastidious organisms such as Streptococcus pneumoniae and Haemophilus influenzae.

Mueller-Hinton with 2% Glucose & Methylene Blue (25ml) This medium is intended for use as a means of differentiation of Candida spp. based on Mueller-Hinton Agar base. The medium is modified by the addition of Glucose and Methylene Blue indicator and is the recommended media for the susceptibility testing of Yeasts according to the CLSI M44-A2 document.

A selective medium for the isolation of fungi, particularly dermatophytes from clinical specimens, Mycological Agar is suitable for use in all areas of Mycology. The medium inhibits most bacteria due to the addition of Chloramphenicol which is added to reduce the risk of bacterial contamination when processing material that may be heavily contaminated particularly with Coliforms. Cycloheximide is also added to suppress the growth of yeasts and saprophytic fungi.