ABSTRACT
        Background and Objective: Campylobacters are infectious zoonotic agents, and among the main bacterial causes of gastroenteritis in humans. Studies have shown that Campylobacter jejuni is of the main causes of infection among humans. Detection of these infectious agents in water resources is of great importance for maintaining the health of humans. Therefore, the aim of this study was molecular detection of C. jejuni strains in surface water samples collected from Rasht, Iran.
       Methods: This cross-sectional descriptive study was performed on 45 surface water samples collected from the city of Rasht. After culture and isolation of bacteria, the molecular detection of C. jejuni was carried out using hipO-specific primers. Presence of cytolethal distending toxin (cdt) gene in positive samples was evaluated by polymerase chain reaction using cdtC-specific primers.
        Results: Of 45 samples, seven (15.5%) were positive for C. jejuni contamination, five of which (71.4%) had the cdtC gene.
Conclusion: The prevalence of toxin-producing C. jejuni in surface waters of Rasht is notable. Therefore, it is recommended to take necessary measures for controlling the spread of this microorganism.
       Keywords: Campylobacter jejuni, Surface water, cdt gene, PCR.

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.