EPEC, EAEC and STEC in stool specimens: prevalence and molecular epidemiology of isolates

Stool specimens of Finns (n = 695) with (n = 603) and without (n = 92) diarrhea were studied for enteropathogenic (EPEC), enteroaggregative (EAEC) and Shiga toxin-producing (STEC) Escherichia coli by PCR. The specific isolates were subsequently investigated for their O:H serotypes and were genotyped by pulsed-field gel electrophoresis (PFGE). A subset (n = 506) of the diarrheal and all non-diarrheal specimens were also searched for conventional enteric bacterial pathogens by standard methods. Diarrheagenic E. coli were found in 5.5% and other enteric pathogens in 6.7% of the patients with and in 2.2% and 1.1% of the subjects without diarrhea, respectively. Campylobacter (3.8%), EPEC (3.2%) and Salmonella (2.0%) were the most common findings, and were detected in diarrheal patients only. STEC were associated with bloody diarrhea (8/9 isolates), whereas EAEC were equally common (1%) in diarrheal and non-diarrheal subjects. Great genomial heterogeneity was seen among diarrheagenic E. coli, and only one EPEC isolate belonged to the "classic" EPEC serogroup (O55).