• Cetrimide agar is a selective medium for the isolation and detection of Pseudomonas aeruginosa from pharmaceutical, clinical and cosmetic samples. The formulation is complaint with the requirements of the Harmonised USP/EP/JP. Detection is achieved using the unique ability of P. aeruginosa to produce the water soluble, bright green pigment pyocyanin. The production of this pigment is stimulated by the presence of magnesium chloride and di-potassium sulphate in the medium. The addition of glycerol (10ml/l) is required as this compound serves as an energy source. Cetrimide, a quaternary ammonium compound, is also present to suppress the growth of other Pseudomonas spp. as well as Gram-negative and Gram-positive organisms. Pancreatic digest of gelatin provides the required nitrogen, carbon and vitamins. Related Supplements :
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  • 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.  
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  • This is a selective enrichment broth for the isolation of Salmonella spp. primarily from food and food product samples and conforms to the requirements ISO 6579:2002. It can however be used in other areas including clinical and environmental specimens. Salmonella spp. reduce tetrathionate and will proliferate in the medium whilst most other enteric organisms are inhibited. Unlike the older traditional tetrathionate broth the addition of novobiocin (40 mg/l) improves the inhibition of Proteus spp. Immediately prior to use it is necessary to add 20 ml/l of 2% iodine/iodide solution (BM0946). Once the iodine/iodide solution has been added the medium should be used immediately and cannot be stored for future use. NB: As this is an opaque medium, the turbidity of the broth alone cannot be used as an indication of growth. Related Supplements : LS0024 Novobiocin Supplement (20mgs/L)
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  • Plate Count Agar is formulated to the A.P.H.A. specification developed by Buchbinder et al. This medium is intended for use in food, dairy and water bacteriology to perform Total Viable Counts. Tryptone and yeast extract provide the required carbon, nitrogen and vitamins. Glucose is a fermentable carbohydrate.  
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  • Violet Red Bile Agar is a medium for the enumeration of coliform organisms in food and dairy products and conforms to American Public Health Association (APHA). Yeast extract and enzymatic digest of gelatin provides the required carbon, nitrogen and vitamins. Sodium chloride maintains the osmotic balance. The medium is made selective by the inclusion of bile salts and crystal violet to inhibit Gram-positive and non-enteric organisms. Lactose is a fermentable carbohydrate and neutral red is a pH indicator. Lactose fermenters produce red/purple colonies often surrounded by a halo of the same colour. Non lactose fermenters produce pale colonies. Selectivity can be increased by incubation at 42-44ºC.  
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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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  • Violet Red Bile Glucose Agar (VRBGA) is a selective medium for the isolation and enumeration of Enterobacteriaceae in food products. It is a modification of the original Violet Red Bile Agar with the lactose being replaced with glucose. As all Enterobacteriaceae ferment glucose VRBGA allows for a wider range of organisms to be detected. This medium conforms to the requirements of the Harmonised USP/EP/JP. Yeast extract and pancreatic digest of gelatin provide the required carbon, nitrogen and vitamins. Glucose is a fermentable carbohydrate and neutral red is a pH indicator. Sodium chloride maintains the osmotic balance. The medium is made selective by the inclusion of bile salts and crystal violet to inhibit Gram-positive and non-enteric organisms.
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  • Sabouraud dextrose agar with chloramphenicol is a selective medium for the isolation of yeasts and fungi suitable for use in all areas of mycology. This medium is a modification of that originally described by Sabouraud. The tryptone and meat peptone provide the required nitrogen and vitamins. The high concentration of dextrose provides an energy source for yeasts and fungi while, in tandem with the acidic pH (5.6), providing some selective properties. Chloramphenicol is included to increase the selectivity of the medium inhibiting a range of Gram-positive and Gram-negative bacteria.
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