O:8 serotype Yersinia enterocolitica strains in China.

ABSTRACT

Serotypes O3, O8 and O9 Yersinia enterocolitica strains carrying virulence determinants are common pathogens causing human infections. In many years of surveillance in China for Y. enterocolitica, no pathogenic O8 strains have been found where the isolated O8 serotypes lacked the major virulence genes and in contrast to O3 and O9 strains, none of the O8 isolates were from humans. These O8 isolates lack ail, ystA, yadA and virF genes but possess the ystB gene and all belong to Biotype 1A. These O8 strains did not kill mice and could protect immunized mice against challenge with a pathogenic O8 strain. Compared to the Chinese pathogenic O3 and O9 strains which have similar pulsed-field gel electrophoresis patterns, the 39 Chinese O8 animal and food isolates were different from the pathogenic O8 reference strains. This suggests the O8 strains lacking virulence determinants may not disseminate rapidly in humans and are maintained in animal reservoirs; and therefore exhibit higher variance and divergence from the virulent type.