Detection Of Virulence Genes Of Escherichia Coli Harboring High Pathogenicity Island Of Yersinia Enterocolitica Isolated In China

The pathogenic strains of Yersinia enterocolitica carry a 45-kb high pathogenicity island(HPI) comprising iron-uptake-related genes such as irp1-irp2 and fyuA, which has been observed in 93% of the 60 entero-adhesive E.coli {EAEC} strains and 80% of the E. coli isolated from blood samples. With irp2 gene as probe, we have isolated HPI-harboring E.coli from various provinces of China. The isolation rates were 27.05% (436/1612) in the untypical E. constrains isolated from diarrhea patients and was 10.23% (9/88) in the untypical E.coli strains isolated from foods samples. To dress the question if other virulence gene were present in this kind of strains, 152 of 436 irp2-hybridized strains were re-confirmed and selected for this study. The virulence genes or putative virulence genes detected by PCR or hybridization include heat stable toxin (st) & heat labile toxin(lt) for enterotoxigenic E.coli(ETEC), invasive plasmid antigen B (ipaB) for enteroinvasive E.coli(EIEC), EPEC adherence factor (eaf), EPEC secretion protein C( espc) for enteropathogenic E.coli(EPEC), hemolysin (hlyA) and shiga toxins ( sltl and slt2) for enterohaemorrhagic E.coli(EHEC) and EAggEC probe for entero-aggregative E.coli(EAggEC). The prrA and yc73 genes of pathogenicity associated island (PAI) of urepathogenic E.coli (UPEC) and "O" island 28 (RTX 615) gene was also detected, the later was a newly discovered putative pathogenicity island in E.coli O157:H7. The results indicated that the HPI-harboring E.coli isolates could not be identified as known categories of diarrheagenic E.coli by the virulence genes with diagnostic value. It was also observed that PAI genes of UPEC, such as yc73 and irp2, were detected in 47 of 82(57.3%) strians, "O" island 28 was detected in 29 of 82(35.4%) strains, "O" island 115 was detected in 56 of 82(68.3%) strains,"O" island 140 was detected in 47 of 82 (57.3%)strains,and SHI-2 island was detected in 51 of 82 (62.2%) strains. In short, our results indicated that those HPI-harboring E.coli isolates could be divided intoseveral groups basing on the detected virulence genes, and further studies are needed to prove if it contains other virulence genes.