Prevalence and clinical manifestations of Shiga toxin-producing Escherichia coli infections in Austrian children.

The prevalence and clinical manifestations of infections associated with Shiga toxin-producing Escherichia coli (STEC) among Austrian children were assessed. Stool samples from 280 pediatric patients were analyzed by enzyme immunoassay (EIA) for the presence of free fecal Shiga toxin (Stx) 1 and 2, and by culture on sorbitol MacConkey agar. Specimens testing positive by the EIA were subjected to a cytotoxicity assay, polymerase chain reaction analysis, and a colony hybridization test. Direct culture on MacConkey agar demonstrated the presence of three Escherichia coli O157:H7-positive stools. These were also positive by EIA and by the DNA-based methods. An additional six samples were positive by EIA, and in four of these, non-O157 STEC of serotypes O111H-, O146:H-, and O113:H53 could be isolated. Analysis of stools for a variety of enteric pathogens demonstrated that STEC was the third most common bacterial pathogen. The clinical manifestations of STEC infections were difficult to distinguish from those of infections caused by other enteric pathogens, as most patients presented with watery diarrhea. The median age of children with STEC infections was 27.6 months (range, 7 months to 5.75 years); children with Salmonella or Campylobacter infections were younger on average, while those with Rotavirus infections were older. This study demonstrated that although Escherichia coli O157:H7 could be identified with the same sensitivity by both EIA or agar-based methods, the identification of non-O157 STEC strains was enhanced by the use of EIA followed by colony hybridization. Analysis of overnight cultures from 53 STEC isolates revealed that all strains producing Stx1, Stx2, or Stx2c reacted in the EIA. However, culture supernatants from Stx2e-producing Escherichia coli O101 were negative in the EIA. Despite this disadvantage, the EIA is easy to perform and time efficient and can be recommended as a screening test for non-O157 STEC in children with diarrhea.