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Glucose agar allows for the detection of glucose fermentation (with or without gas production) as an identification test for Enterobacteriaceae (ISO 21528) and B.cereus (ISO 7932). It is further enriched by the addition of Yeast Extract. Bromocresol Purple is also included and acts as an indicator of glucose fermentation. -
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 -
Pseudomonas Agar Base with 1% Glycerol & CN Supplement A selective medium for the isolation of Pseudomonas aeruginosa the medium is made selective by the inclusion of Cetrimide and Naladixic Acid (CN) supplement to significantly reduce the enteric organisms particularly Proteus and Klebsiella spp. Magnesium and Potassium salts are included to enhance the production of the pigments pyocyanin and fluorescein. -
This medium can be used as a screening method for the differentiation of enterobacteriaceae based on the ability of some species to utilise citrate as a sole source of carbon. It is often used as a screening test for Klebsiella pneumoniae (positive reaction) while Escherichia coli is negative. Species that metabolize citrate as their sole source of carbon and ammonium as the sole source of nitrogen cause an increase in alkalinity of the medium resulting in a colour change from green to blue due to the presence of the pH indicator bromthymole blue.
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This medium can be used as a screening method for the differentiation of Enterobacteriaceae based on the ability of some species to utilise citrate as a sole source of carbon. It is often used as a screening test for Klebsiella pneumoniae (Positive reaction) while Escherichia coli is negative. Other uses included distinguishing between species of citrate positive Salmonellae (e.g. Salmonella enteritidis) and those that are negative (e.g. Salmonella typhi and Salmonella paratyphi A). The medium is inoculated by stabbing the organism (in pure culture) into the medium. A positive result produces a change of colour from green to bright blue and a negative reaction leaves the colour unchanged.
