Characterization of strains isolated from human stool samples: results from the prospective German prevalence study Arcopath.

BACKGROUND

constitute emerging food- and waterborne pathogens causing gastroenteritis in humans, but the underlying mechanisms are only incompletely understood. We therefore characterized isolates derived from human stool samples that had been collected during a prospective prevalence study in Germany in vitro. Thirty-six bacterial isolates belonging to the species (n = 24), (n = 10) and (n = 2) were genotyped by ERIC-PCR, the presence of 10 putative virulence genes was assessed and cytotoxic effects on the human intestinal cell line HT-29/B6 were analyzed applying the WST-assay.

RESULTS

Genotyping revealed high genetic diversity within the species , and . Both, and encoded for a large number of putative virulence genes, while fewer genes were detectable in isolates. Notably, the three cytolethal distending toxin (CDT) genes , and were abundant in both isolates. Furthermore, all and , but only one of the isolates exerted cytotoxic effects.

CONCLUSIONS

Our study provides evidence for the abundance of putative virulence genes in isolates and prominent cytotoxic effects of and in vitro. The presence of , , in points towards CDT secretion as potential mechanism underlying cytotoxicity as opposed to . However, the association of the virulence factors detected and human morbidity should be addressed in future studies.