Additionally, susceptibilities to ampicillin and oxytetracycline were determined for V. cholerae species-specific-PCR positive isolates(n ¼ 375) retrieved by the direct-spreading method using TCBS agar as described above. Susceptibility to oxytetracycline was also determined for V. parahaemolyticus species-specific-PCR positive isolates (n ¼ 230) retrieved by the direct-spreading method. Resistant isolates were subjected to the biochemical tests for confirmation of bacterial species.