Reliability in the detection of Escherichia coli based on their serogroup as a cause of sporadic and epidemic occurrence of enterocolitis]

The purpose of this study was to determine the presence of virulence factors (heat-labile, heat-stable enterotoxin, verotoxin, invasiveness, localized, aggregative and diffuse adherence) among E. coli strains isolated from sporadic cases and outbreaks of enterocolitis, which belonged to serogroups characteristic for enteropathogenic E. coli. Serogroup was determined in 57.2% of 622 strains isolated from sporadic cases, and among them virulence factors were detected in 23.6%. Serogroup was also determined in 73.3% of 90 outbreaks isolates tested and virulence factors were detected in 97% of them. The detection rate of virulence factors rarely exceeded 50% among strains belonging to any of serogroup that was determined. The obtained data suggested that the identification of E. coli as a causative agent of enterocolitis by serogroup determination was a reliable method in outbreaks, but not in sporadic cases of this disease.