OCCURRENCE OF UREASE-POSITIVE VIBRIO-PARAHAEMOLYTICUS IN KANAGAWA, JAPAN, WITH SPECIFIC REFERENCE TO PRESENCE OF THERMOSTABLE DIRECT HEMOLYSIN (TDH) AND THE TDH-RELATED-HEMOLYSIN GENES

A total of 132 strains of V. parahaemolyticus isolated from patients a nd from the suspected causal food items of past food poisoning cases o ccurring in Kanagawa Prefecture, Japan, were examined for the ability to hydrolyze urea, with specific reference to the presence of the ther mostable direct hemolysin gene (tdh) and the gene for thermostable dir ect hemolysin-related hemolysin (trh). Ten strains belonging to five d ifferent O-antigen serotypes were positive for urea hydrolysis (UH+), and four of these strains did not early tdh. A total of 106 strains ca rried tdh, but less than 6% of them were UH+, whereas all trh-carrying strains were UH+. The evidence suggests that urea hydrolysis is not a reliable marker for identifying tdh-carrying V. parahaemolyticus stra ins in Japan (the Pacific Northeast) but may be a marker for trh-carry ing strains.