Abstract

TANARO, José D.; LOUND, Liliana H.  and  DOMINGUEZ, M. M.. Detection of Escherichia coli O157:H7 in environ- mental waters, lees and rumen of bovines in urban proximities. Cienc. docencia tecnol. [online]. 2006, n.32, pp.207-218. ISSN 1851-1716.

Escherichia coli  O157:H7 was searched in 35 water samples of the Gualeguaychú River and other small affluent streams, 25 samples of bovine faeces, and 40 samples of rumen. The adopted scheme consisted of a selective enrichment in modified broth EC added of novobiocina (42ºC, 18-24hs), followed by a magnetic inmunoconcentration and later isolation in Agar MacConkey sorbitol with addition of Telurito of Potassium and ID^® medium (37ºC 18 - 24 h). Biochemical and serological screening was performed for the typical colonies, and then tests of confirmation were made. The strains isolated were fenotipic and genotipically characterized. Seven strains were obtained from water and one from ruminal content. Five strains were toxin-producing O157:H7 serotype and C biotype, ß-Glucuronidasa (-), EHEC-hly (+). Four of them were Stx ½-producing and the last strain was only Stx2-producing. Another three strains that were O157 serotype lacked of virulence factors.

Keywords : Escherichia coli O157:H7; Water; Rumen; Manure; Immunomagnetic separation.

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