Atypical enteropathogenic Escherichia coli

Abstract

The atypical enteropathogenic Escherichia coli (EPEC), a subgroup of EPEC, has the ability to cause histopathologic attaching and effacing lesions in eukaryotic cells, but lacks the virulence-associated EPEC adherence factor plasmid. The aEPEC strains may harbor virulence markers of other Diarrheagenic E. coli pathogroups as well as of extraintestinal pathogenic E. coli strains. This observation led to the assumption that aEPEC strains comprise a very heterogeneous group with diverse additional virulence mechanisms that altogether can modulate the disease outcome or their occurrence in asymptomatic subjects. While the prevalence of typical EPEC strains has declined in the last decade in most geographic areas studied, aEPEC strains are considered emerging enteropathogens that have been detected worldwide. In addition, the detection of aEPEC in different animal species, as well as in food and environmental samples, suggests that at least some aEPEC infections may be zoonotic. Herein, we review the recent achievements in the knowledge of the virulence properties, genetic background, and epidemiology of aEPEC infections in the America. Despite the recent advances, the need of discriminating between strains that can cause diarrhea and those that promote asymptomatic infections is a current motivation for further studies in the field.