Isolation and virulence factors of verocytotoxin-producing Escherichia coli in human stool samples.

OBJECTIVE: To evaluate the isolation rate of O157 and non-O157 verocytotoxin-producing Escherichia coli (VTEC) strains, to study the occurrence of additional virulence factors and to correlate these with clinical symptoms. METHODS: Over more than 5 years, 17 296 unduplicated fecal samples submitted for routine culture were screened for VTEC by a single PCR detecting VT1, VT2 and its variants. Verocytotoxin B subunit genotypes of the isolates obtained by testing individual colonies in positive samples were determined by a polymerase chain reaction---restriction fragment length polymorphism (PCR---RFLP) technique, the eaeA gene and the 60-MDa virulence plasmid by PCR, and the hemolytic phenotype by using CaCl2-washed blood agar.

Growing Concerns and Recent Outbreaks Involving Non-O157:H7 Serotypes of Verotoxigenic Escherichia coli.

Verocytotoxin-producing E. coli (VTEC) of serotype O157:H7 have been shown to be important agents of foodborne disease in humans worldwide. While the majority of research effort has been targeted on this serotype it is becoming more evident that other serotypes of VTEC can also be associated with human disease.