Application of pulsed-field gel electrophoresis to the investigation of a nosocomial outbreak of Vibrio parahaemolyticus.

The method of pulsed-field gel electrophoresis (PFGE) for Vibrio parahaemolyticus was first published in 1996. Since then, its application has been seldom reported in the literature. A food poisoning outbreak due to V. parahaemolyticus occurred in five wards of a hospital was investigated using this method. Twenty-five patients were involved and all of them had eaten food supplied by the hospital. Of the 15 cases whose stools were available for culture, only four cultures yielded V. parahaemolyticus. All four isolates were serotype K6 and were indistinguishable or closely related to each other based on PFGE patterns. Two isolates from food were recovered and they presented different characterizations from the patient isolates in both serotype and PFGE pattern. Successful typing by PFGE to identify the outbreak strain and differentiate V. parahaemolyticus strains between patient and food isolates in this study suggests the usefulness of PFGE for V. parahaemolyticus, the leading cause of food poisoning in Taiwan.