Escherichia coli pathotypes associated with diarrhea in Romanian children younger than 5 years of age.

To document the association of pathogenic Escherichia coli with diarrhea in Romanian children, 250 E. coli fecal isolates from children under 5 years of age were PCR-screened for well-recognized virulence determinants, as well as for their phylogenetic background. The putative diarrheagenic E. coli (DEC) were investigated for susceptibility to various antibiotics. Overall, 61 E. coli isolates were classified as enteroaggregative E. coli (29 isolates), atypical enteropathogenic E. coli (22 isolates), enterotoxigenic E. coli (8 isolates), and verotoxin-producing E. coli (1 isolate), and one isolate was categorized as unconventional DEC. Only 8 of the PCR-positive isolates would have been assumed to be pathogenic based on their O antigenicity, which highlights the limited effectiveness of serotyping. More than a half (51%) of the pathogenic isolates expressed a multidrug-resistant phenotype, which raises concerns about the therapeutic pediatric approach. The DEC isolates were heterogeneous phylogenetically, deriving from all four major groups: A (31 isolates), B2 (14 isolates), B1 (10 isolates), and D (6 isolates), respectively. Thus, the phylogenetic descent was less significant than the virulence gene content. Our findings document the importance of DEC as a cause of childhood diarrhea in Romania, providing evidence that efforts should be made to estimate the burden of infections by etiology for a better medical approach.