Shiga toxin-producing Escherichia coli in healthy young beef steers from Argentina: prevalence and virulence properties.

Between July 1999 and December 2000, the prevalence of Shiga toxin-producing Escherichia coli (STEC) was established in 200 Argentine healthy young beef steers (14-16 months old) grown under local production systems with a feed grain period of 3-4 months, and the STEC strains isolated were examined in regard to their phenotypic and genotypic characteristics. Stool samples (n = 70) and rectal swabs (n = 130) were taken at the slaughterhouse level. By polymerase chain reaction (PCR), Shiga toxin (stx) gene sequences were detected in 69% of the samples.

Evaluation of a QIAamp DNA stool purification kit for Shiga-toxigenic Escherichia coli detection in bovine fecal swabs by PCR.

A commercial kit intended for Taq polymerase inhibitor removal was tested to detect Shiga-toxigenic Escherichia coli (STEC) by polymersase chain reaction (PCR) directly from cattle fecal samples. Forty-five samples were analysed for the presence of stx genes. Results were compared to those obtained by two other methods: amplification of DNA purified by a non-commercial procedure (heat lysis protocol), and amplification of DNA from samples cultured in solid media, commonly used in our lab.

Detection of Shiga toxin-producing Escherichia coli by PCR in cattle in Argentina. Evaluation of two procedures.

Different experimental approaches were evaluated for their ability to detect stx genes by PCR and identify Shiga toxin-producing Escherichia coli (STEC) in bovine fecal samples. One hundred and sixty fecal samples from steers in Argentina were processed by protocols that involved: (1) enrichment of fecal samples and DNA extraction using a commercially available kit (Protocol A); (2) plating on selective media after enrichment of the fecal sample followed by heat-lysis DNA extraction from the confluent growth zone (Protocol B); (3) analysis of individual colonies isolated from direct fecal culture on MacConkey agar and sorbitol MacConkey agar supplemented with cefixime and potassium tellurite (Protocol C), used as Gold Standard. PCR performed on bacteria from the confluent growth zone (Protocol B) proved to be the most sensitive methodology.

Soy protein isolate added to vacuum-packaged chorizos: effect on drip loss, quality characteristics and stability during refrigerated storage.

Chorizo is a raw sausage, which is manufactured with beef, pork meat and pork fat, additives and spices. In Argentina, the expenditure of chorizo is through butchery and supermarkets where the product can be found packaged in both polyethylene films and vacuum sealed pouches. In the latter type of packaging an appearance problem has been detected in relation to drip loss.