Canine feces as a reservoir of extraintestinal pathogenic Escherichia coli

To test the canine reservoir hypothesis of extraintestinal pathogenic Esche richia coli (ExPEC), 63 environmental canine fecal deposits were evaluated for the presence of ExPEC by a combination of selective culturing, extended virulence genotyping, hemagglutination testing, O serotyping, and PCR-base d phylotyping. Overall, 30% of canine fecal samples (56% of those that yiel ded viable E. coli) contained papG-positive E. coli, usually as the predomi nant E. coli strain and always possessing papG allele III (which encodes va riant III of the P-fimbrial adhesin molecule PapG). Multiple other virulenc e-associated genes typical of human ExPEC were prevalent among the canine f ecal isolates. According to serotyping, virulence genotyping, and random am plified polymorphic DNA analysis, over 50% of papG-positive fecal E. coli c ould be directly correlated with specific human clinical isolates from pati ents with cystitis, pyelonephritis, bacteremia, or meningitis, including ar chetypal human ExPEC strains 536, CP9, and RS218. Five canine fecal isolate s and (clonally related) archetypal human pyelonephritis isolate 536 were f ound to share a novel allele of papA (which encodes the P-fimbrial structur al subunit PapA). These data confirm that ExPEC representing known virulent clones are highly prevalent in canine feces, which consequently may provid e a reservoir of ExPEC for acquisition by humans.