Ribotyping of Vibrio parahaemolyticus isolates obtained from food poisoning outbreaks in Taiwan.

Vibrio parahaemolyticus is a prevalent food-borne pathogen in Taiwan, Japan and other Asian countries. This work presents a novel ribotyping method for the molecular epidemiological examination of this pathogen. Genomic DNA was fragmented by HindIII digestion and hybridized with cDNA probe for Escherichia coli 16S and 23S RNA genes. A total of 121 isolates obtained from outbreaks during 1992 and 1994 in Taiwan were characterized by this ribotyping method. Four to seventeen restricted fragments were visualized in these isolates. After hierarchical cluster analysis, these isolates were grouped into thirty different ribotypes. In addition, A3, A7, E3 and F1 were the major ribotypes, consisting of 22.3, 13.2, 9.1, and 8.3% of the isolates, respectively. A, E, F, G and B were the major groups, consisting of 46.2, 14.0, 9.1, 6.7, and 6.7% of the isolates, respectively. The discriminatory ability of this ribotyping method, as determined by Simpson's index of diversity, was 0.93, which closely resembled that of a previously reported pulsed-field gel electrophoresis method.