The objective of this study were to compare the ability to detect V. cholerae and V. parahaemolyticus by conventional methods using TCBS, CAV medium and PCR method
and also to identify the presence of virulence genes of V. cholerae, V. parahaemolyticus from fresh seafood by using m-PCR technique. A total of 313 samples (126 from fillet fish, 52 from shrimp and 135 from clam) were collected at Center of Analytical Services and Experimentation in HCMC (CASE). The results was showed that the frequency of V. parahaemolyticus was 22.0 percent in TCBS medium, 37.7 percent in CAV and 43.5 percent by PCR method. Similar, the frequency of V. cholerae was 12.5 percent in TCBS, 24.3 percent in CAV and 27.5 percent by PCR method. In order to identify cholera toxin of V. cholerae, m-PCR2 was performed with the extracted DNA from enrichment broth of 86 samples, 39 isolates of V. cholerae in TCBS and 76 isolates in CAV. The result was showed that the frequency of V. cholerae 01/0139 serogroup and V. cholerae non-01/non-0139 possessed cholera toxin from the enrichment broth were higher than from the isolates in TCBS and CAV, in contrast, the frequency of V. cholerae 01/0139 serogroup non-carried cholera toxin from the enrichment broth and from the isolates in TCBS and CAV was non-significantly difference. To identify the hemolytic gene of V. parahaemolyticus, m-PCR3 was performed with the extracted DNA from enrichment broth of 136 samples, 69 isolates of V. parahaemolyticus from TCBS and 118 isolates from CA V. The result was showed that the frequency of tdh gene from the enrichment broth higher than from the isolates, 100 percent the enriched samples and isolates were detected tlh gene.