Establishment of molecular typing database for Vibrio parahaemolyticus

Objective To conduct pulse field gel electrophoresis (PFGE) for the Vibrio (V.) parahaemolyticus strains isolated in 8 provinces (municipality) in China and establish a PFGE molecular typing database of V. parahaemolyticus. Methods A total of 617 V. parahaemolyticus strains isolated between 2005 and 2014 were typed by SfiⅠ-digested PFGE. PFGE patterns were analyzed and the database was established with software BioNumerics 5.01. Results The established V. parahaemolyticus molecular typing database included 617 pieces of strain information. All the analyzed V. parahaemolyticus strains were divided into 360 PFGE patterns. The PFGE patterns were encoded according to the regulation of PulseNet China. The similarity index ranged from 35.8% to 99.6%. The 237 strains of V. parahaemolyticus isolated from environment or foods had 221 PFGE patterns, while the 345 strains of V. parahaemolyticus isolated from diarrhea patients had 127 PFGE patterns. V. parahaemolyticus strains with identical serotype had same or similar PFGE patterns, while those with different serotypes had quite different PFGE patterns. Multi predominant PFGE patterns were observed in pandemic serotypes of V. parahaemolyticus i.e. O3:K6 and O4:K8. Conclusion V. parahaemolyticus strains isolated from diarrhea patients showed less diversity than those isolated from foods and environment. PFGE analysis is useful in identifying cases clustering. For diarrhea related V. parahaemolyticus strains, which cluster, intensive epidemiological investigation and source tracking should be carried out.