[Study of possibility of formation of Vibrio parahaemolyticus pandemic clones based on retrospective PCR-screening of clinical strains].

AIM

PCR-genotyping of Vibrio parahaemolyticus strains that had caused sporadic diseases in Novorossiysk from 1973 to 1976.

MATERIALS AND METHODS

24 clinical strains of V. parahaemolyticus isolated in Novorossiysk, most of which belonged to serogroups O4:K12 and O4:K8; 10 O3:K6 strains--causative agents of gastroenteritis outbreak in Vladivostok (1997) and 3 from Japan (1971) were used. PCR genotyping was performed by a set of marker genes of 7 pathogenicity islands (VPaI-1 - VPaI-7) and a number of other pathogenicity factors.

RESULTS

All the strains isolated in 1970s differed significantly by sets of VPaI marker genes. In contrast to causative agents of outbreak in Vladivostok that contain all 7 VPaI genes (that is, members of the pandemic group that had spread globally since 1996) none of the O4:K12 and O4:K8 Novorossiysk strains contained the full set of all the VPaI genes. However this set was distributed among the members of the group.

CONCLUSION

Taking into account that O4:K12 and O4:K8 serogroups are considered by a number of authors as O3:K6 serovariants, PCR-screening data obtained by us allows to assume that horizontal transfer of mobile elements (VPaI) between strains circulating in the region could have led to the formation of pandemic clones already in the 1970s. This implies that in several coastal regions in certain periods of time conditions that favor these process may form, and risk of infection with pandemic clones is associated not only with import of seafood.