Genetic and phylogenetic analysis of Vibrio parahaemolyticus reveals distinct differences in strains from the Pacific Northwest of the U.S.

Genetic and phylogenetic analyses of Vibrio parahaemolyticus (Vp) strains isolated from the U.S. Pacific Northwest demonstrate that clinical isolates are genetically distinct from the environmental isolates. Several environmental isolates are clonally related to strains that have been responsible for Vp-related illnesses world-wide (the pandemic complex) but have not been responsible for illnesses in the Pacific Northwest. While both clinical and a significant proportion of environmental isolates encode one of the putative virulence markers, the thermostable direct hemolysin (tdh), clinical isolates also encoded a second virulence marker, the tdh-related hemolysin (trh). Our findings suggest that V. parahaemolyticus isolates from the Pacific Northwest encoding trh are more likely to be pathogenic than isolates encoding tdh alone