MATERIALS AND METHODS: Samples were collected from four recreational beaches in Malaysia (Port Klang; Bachok; Port Dickson; and Mersing). Thiosulfate-citrate-bile salts-sucrose (TCBS) agar and chromogenic Vibrio agar were used for isolation and identification. Colonies with yellow color on TCBS and green color on chromogenic vibrio (CV) agar were considered to be V. parahaemolyticus and they were subjected to biochemical tests. All V. parahaemolyticus isolates were further subjected to identification using seven specific gene markers.

RESULTS: Seventy-three Vibrio isolates were recovered. Only one gene thermostable direct hemolysin (tdh) from seawater isolates of Vibrio has high virulence gene percentage (95.23%). Two genes alkaline serine protease (asp) and (tdh) had high percentage of virulence (83.87% and 80.64%, respectively) from fish. Comparatively, fish isolates have a higher virulence percentage compared to seawater isolates. Only gene streptomycin resistance B (strB) from seawater had 100% of the resistance genes. All isolates were multi-antibiotic resistant. Seventeen antibiotic resistance patterns were observed. The isolates had plasmids of varying sizes ranging from 2.7 kb to 42.4 kb. Dendrogram based on antibiotic resistance patterns of V. parahaemolyticus isolates discriminated the isolates into three clusters.