Detection of Virulence Genes Tcpa and Ctxb in Isolates from Surface Water and Salt Water Samples in Golestan, Iran

ABSTRACT          Background and Objective: Vibrio is a genus of bacteria that are widely distributed in aquatic environments. The genus includes several important pathogens that endanger farm animals and humans who ingest seafood or water contaminated with the bacteria. Virulence of Vibrio spp. is regulated by ctxAB and tcpA genes. The aim of this study was to determine the prevalence of Vibrio spp., and tcpA and ctxB virulence genes in isolates from surface water and salt water samples collected from Golestan Province, Iran.           Methods: Overall, 115 water samples were collected from the Caspian Sea coast, lagoons and rivers in the Golestan Province. The samples were filtered by membrane filtration method, and enriched in alkaline peptone water with 1% NaCl. The isolates were grown on TCBS agar, and identified by biochemical tests. Presence of the tcpA and ctxB virulence genes was investigated by polymerase chain reaction.           Results: In this study, Vibrio alginolyticus was the predominant species (38%) isolated from the seawater and surface water samples, followed by Vibrio parahaemolyticus (23%), Vibrio harvei (15%), Vibrio fluvialis (14%) and Vibrio damsela (10%). The virulence genes were not detected in any of the isolates found in the study.         Conclusion: This study indicates that V. alginolyticus is the most prevalent Vibrio spp. in surface water and seawater samples collected from the Golestan Province, Iran.           Keywords: Environmental Vibrio, Surface water, ctx B gene, tcpA gene.