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

GIOFFRE A, MEICHTRI L, MILIWEBSKY E, BASCHKIER A, CHILLEMI G, ROMANO MI, SOSA-ESTANI S, CATALDI A, RODRÍGUEZ R, RIVAS M

VETERINARY MICROBIOLOGY

Año: 2002 vol. 87 p. 301 - 313

0378-1135

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. In addition, enrichment for greater than 6 h, enhanced sensitivity. Among eight STEC isolates, four were O8:H19 and four were stx2/eae-negative. An STEC isolate was characterized as O26:H11 with a stx1/eae/EHEC-hlyA genotype, often associated with human disease. Finally, no STEC O157 strains were isolated using these methods.