Pathogenic Escherichia coli O157:H7 and their detection.
Enterohaemorrhagic Escherichia coli O157:H7 is of major concern to the food industry due to high pathogenicity of this foodborne organism. For the detection of these bacteria a special agar medium with a fluorogenic substrate has been developed. The medium uses the characteristics of this E. coli serotype not to ferment sorbitol and not to produce beta-glucuronidase. In contrast, approximately 96% of all other strains of E. coli are sorbitol-positive and nearly all of them are beta-glucuronidase-positive. For discrimination between Proteus and E. coli O157:H7 which are both sorbitol- and beta-glucuronidase-negative, sodium thiosulphate and ferrio ammonium citrate were added. This leads to a brownish colour of the Proteus colonies due to their production of hydrogen sulphide. Growth of the gram-positive flora was inhibited by the addition of sodium deoxycholate.
Pawelzik
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E. Merck Diagnostic Division, Research and Development Darmstadt, FRG.
D000818:Animals; D001431:Bacteriological Techniques; D002417:Cattle; D004755:Enterobacteriaceae / Q000302:isolation & purification; D004926:Escherichia coli / Q000302:isolation & purification* / Q000472:pathogenicity; D005069:Evaluation Studies as Topic; D005516:Food Microbiology; D005517:Foodborne Diseases / Q000382:microbiology; D006801:Humans; D008460:Meat