1997 Volume 71 Issue 12 Pages 1221-1225
One hundred and twenty-five strains of Vibrio parahaemolyticus carrying both the tdh and trh genes were selected from the strains isolated from the travelers with diarrhea by an hybridization test using polynucleotide probes. The levels of TDH produced by these strains and the association between the TDH levels and related chracteristics in these strains were analyzed. The TDH level varied greatly from strain to strain, but none of the levels was as high as that of the typical Kanagawa phenomenon-positive strains. The strains were classified into “TDH producer”(18 strains), “Low-level TDH producer”(85 strains), and “No TDH producer”(22 strains) based on the results of a modified Elek test and the hemolysis assay on Wagatsuma agar. The highest TDH level achieved by the “TDH produce”was twofold lower than that of the Kanagawa phenomenon-positive strains as assayed by the RPLA method.
All strains possessed the toxR gene. The trhl and trh2 genes were detected in, respectively, 105 and 20 strains, and no correlation existed between the type of the trh gene and the levels of TDH produced. Considerable restriction fragment length polymorphism was observed with the tdh gene-bearing HindlIl DNA fragment in different strains, but it was not related with the TDH level.
