Abstract
A total of 149 samples including 50 samples of seawater, 50 samples of sea mud and 49 shellfish obtained at 6 points in the Tokyo Bay areas between 1999 and 2004 were examined for Vibrio parahaemolyticus and other pathogenic vibrios.
V.parahaemolyticus was isolated from all Samples. The number of V.parahaemolyticus in most sea mud samples were 10-100 times higher than that in seawater samples.NAG vibrio, V. fluvialis, V. mimicus, V. furnissii, and V. choleme O1 (cholera toxin negative) were isolated from 51 (34.2%), 21 (14.1%), 13 (8.7%), 8 (5.4%), and 2 (1.3%) of the samples, respectively. NAG vibrio was more frequently isolated from seawater samples than sea mud or shellfish samples. V.mimicus and V.fluvialis were more frequently isolated from the area where the salinity of the seawater was low.These findings show that V.parahaemolyticus and other pathogenic vibrios examind are widely distributed in the Tokyo Bay, but the distribution of different pathogenic vibrios varieds lightly by area.
The most probable number of V.parahaemolyticus in seawater, sea mud and shellfish were compared by one-step and two-step enrichment culture methods.However, the results did not significantly differ between the two methods.
Although V.parahaemolyticus strains belonging to serotype O3: K6 were isolated from 16 samples, only one was a tdh-positive strain and there were no trh-positive O3: K6 strains in seawater produce neither TDH nor TRH. Total of 7 tdh-positive strains, 6 trh-positive strains and 5 tdh and trh-positive str-late tdh- and/or trh-positive V.parahaemolyticus from the culture broth samples in which the tdh or trh gene was detected by PCR method.
