The pathogenicity island gene irp-2 of Yersinia enterocolitica was detected in enteric Shiga-like-toxin-producing and invasive E. coli isolated in China

Objective: Detection of the pathogenicity island gene irp-2 of Yersinia enterocolitica species from enteric Shiga-like-toxin-producing and invasive Escherichia coli (ESIEC) strains isolated in various provinces of China. Methods: Colony hybridization, DNA dot hybridization and polymerase chain reaction (PCR). Results: By colony blots, 67 of the 371 (18.06%) strains of ESIEC were hybridized with the irp-2 gene probe. The replicon of irp-2 gene was identified by PCR method in 64 of 67 strains (95 5%) hybridized with irp-2 probe. And, one of the 67 strains hybridized with ipaB gene probe of entero-invasive E. coli (EIEC). A few strains of EIEC have been proved to be irp-2 gene positive. 20 irp-2-positive and 20 irp-2-negative strains of ESIEC, demonstrated by colony hybridization and PCR methods were selected to test irp-2 and ipaB genes by DNA dot blots. 38 of 40 strains were shown to be identical. Conclusion: The irp-2 of Yersinia species is widely existed among the ESIEC strains isolated in China, and the irp-2⁺ ipaB^- could be used as one of the diagnostic marker for some strain that were named ESIEC before.