Subspecies typing of Vibrio parahaemolyticus by pulsed-field gel electrophoresis.

Vibrio parahaemolyticus is one of the most important food-borne pathogens in Taiwan, Japan, and other costal regions. We report on the development of a pulsed-field gel electrophoresis (PFGE) method for the molecular typing of this pathogen. Genomic DNA was digested with SfiI, and the fragments were resolved on 1% agarose with a contour-clamped homogeneous electric field apparatus set at 190 V and a pulse time of 3 to 80 s. A total of 130 selected isolates obtained from outbreaks during 1993 and 1994 on Taiwan were also characterized by this PFGE method. These isolates were grouped into 14 PFGE types which consisted on one to six patterns, and a total of 39 patterns were identified. Most of these domestic clinical isolates could be clustered into several major types (types A, B, C, and G). These major types showed relatively low degrees of similarity to several foreign strains and other domestic but environmental strains. Strain CCRC12863, which originated from Japan, was close to the group consisting of F, G, and H PFGE types, suggesting a clonal relationship between this Japanese strain and other domestic isolates.