Toxic genes and antibiotic resistance patterns in Vibrio Parahaemolyticus isolates from caught fish of the Caspian Sea

Vibrio parahaemolyticus (V. parahaemolyticus) is a marine bacterium that is widely acknowledged as a predominant causative agent responsible for bacterial foodborne outbreaks on a global scale. The objective of our study was to determine the prevalence of toxin-producing genes and antibiotic resistance patterns in V. parahaemolyticus isolates obtained from fish caught in the Caspian Sea. We conducted a descriptive cross-sectional study in which we collected ۲۲۰ fish samples from the Caspian Sea, comprising four fish species (Rutilus kutum, Mullet, Carp, Perch). The samples underwent enriched and culture for bacteriological and biochemical examination. The isolates were confirmed using the ۱۶S rRNA flagella-specific gene of V. parahaemolyticus and then subjected to antimicrobial susceptibility testing using the disk-diffusion method. Additionally, PCR was employed to investigate the presence of three virulence genes (toxR, tdh, and trh genes). Out of the total fish samples, ۴۰ (۱۸.۱%) were found to be contaminated with V. parahaemolyticus. All ۴۰ confirmed isolates possessed the toxR gene and ۲۹ (۷۲.۵%) of them harbored the tdh gene, while none of them contained the trh gene. The majority of the isolates exhibited susceptibility to ciprofloxacin (۹۷.۵%) and chloramphenicol (۹۲.۵%), but demonstrated resistance to amoxicillin (۹۵%) and doxycycline (۹۵%). The findings of this study yield valuable insights in to the microbial contamination of fish caught in the Caspian Sea. The high prevalence of V. parahaemolyticus in seafood and the identification of multidrug-resistant isolates underscore a potential risk to human health. Therefore, appropriate control measures should be implemented to mitigate the risk of contamination.

Keywords:

Vibrio parahaemolyticus , Marine environment , Seafood-borne illness , virulence genes