A total of 240 samples of marketed shrimp and shellfish were collected from Dong Nai province and Ho Chi Minh city. Two enrichment media were used: ASPW (alkaline salt peptone water) and ASPW supplemented with polymycin B 50UI and 3 percent NaCl, DNA extracted from enriched samples was examined by three m-PCR reactions to identify (i) the species of V. cholerae (m-PCR 1)
(ii) the O1 and O139 serogroups (m-PCR2)
and the biotypes (m-PCR3). Besides, isolates from enriched media were examined using conventional methods (biochemical tests) and m-PCRs. By m-PCR1, V. cholerae was detected from 44.2 percent of the enriched samples in ASPW medium and 45.8 percent of the enriched samples in supplemented ASPW medium, while the bacteria were isolated from only 41.3 percent and 10.0 percent of the samples (respectively). Using m-PCR2, two out of 106 ASPW-enriched samples and two out of 110 enriched samples supplemented with polymycin B were found positive for ctxA and rfbO1
8 and 11 samples were positive for ctxA and rfbO139
2 and 4 samples, for rfbO1
2 and 4 samples, for rfbO139
and ctxA was detected from 13 and 18 samples (respectively). Furthermore, ctxA, rfbO1 and rfbO139 were simultaneously detected from two samples enriched in supplemented ASPW broth. Using extracted DNA of detected isolates, the result of m-PCR2 of identification of serogroups from 99 samples in ASPW and 24 samples in supplemented ASPW, 5 and 3 samples were positive for toxigenic V. cholerae belonging to serogroup O139, 11 and 5 samples were positive for non-toxigenic V. cholerae O1/O139
and 5 and 2 samples were positive for V. eholerae non-O1/O139 carried CT ( respectively). The results from m-PCR3 showed that tcpA EI Tor was only detected from three of six samples. Antibiotic resistance tests showed that V. eholerae isolates were completely resistant to colistine
highly resistant to oxacillin
and were sensitive to doxycycline and norfloxacin.