Genetic diversity among Norwegian<i>Vibrio parahaemolyticus</i>

Abstract

AIMS: To examine the variability among environmental Vibrio parahaemolyticus (including trh+ isolates) from Norway, and to compare these to clinical isolates and isolates from imported foods. METHODS AND RESULTS: A total of 246 V. parahaemolyticus were successfully digested with NotI, and the fragments were separated by pulsed field gel electrophoresis (PFGE). The isolates could be divided into 72 clusters and 103 pulsotypes. Eleven clusters contained 4-31 environmental isolates, and the isolates within these clusters greatly varied with respect to origin. None of the trh+ and /or tdh+ isolates clustered with trh-/tdh- isolates. The trh+ environmental isolates included in the study belonged to two separate clusters. A subset of isolates was serotyped, and great serotype diversity was observed among the environmental V. parahaemolyticus. The clinical isolates included O3:K6 and O3:KUT, and these were identical or related to a pandemic reference strain by PFGE. CONCLUSIONS: Environmental V. parahaemolyticus (including trh+) were genetically diverse, but certain variants occurred throughout the coastal environment, and some were persistent over time. SIGNIFICANCE AND IMPACT OF THE STUDY: Although trh+ V. parahaemolyticus persisted in the Norwegian environment, no evidence indicated that indigenous isolates have caused disease.