Molecular Characterization, Antibiotic Resistance Pattern, and Biofilm Formation of Vibrio Parahaemolyticus Isolated from Tropical Seafood.

Background: Vibrio parahaemolyticus in seafood poses a major public health concern, particularly in tropical regions.

Objective: The present study aims to isolate, assess antibiotic susceptibility, and determine the biofilm-forming ability of V. parahaemolyticus strains isolated from seafood sold in Cochin, India.

Methods: One hundred seafood samples were collected from retail markets in Cochin and analyzed for V. parahaemolyticus. Phenotypic identification was confirmed through biochemical assays and molecular characterization using polymerase chain reaction (PCR) targeting toxR, tdh, and trh genes. Biofilm formation was assessed using the microtiter plate-crystal violet assay, and antibiotic resistance was determined using the disc diffusion method.

Results: V. parahaemolyticus was detected in 43.0% (43/100) of the total seafood analyzed. A total of 43 isolates were confirmed by the toxR gene, of which five carried the tdh gene, while none harbored the trh gene. Antimicrobial susceptibility testing revealed 100% resistance to ampicillin, whereas all isolates were fully susceptible to chloramphenicol. The multiple antibiotic resistance (MAR) index ranged from 0.13 to 0.50. Notably, some multidrug-resistant isolates exhibited strong biofilm formation at 37°C.

Conclusion: The high prevalence of antibiotic-resistant V. parahaemolyticus in seafood sold in Cochin and their ability to form biofilms underscores the need for rigorous monitoring and effective control strategies to safeguard public health.

Highlights: The overall prevalence of V. parahaemolyticus in seafood from the retail market was 43.0%. The tdh gene was detected in five isolates, and none had the trh gene. All isolates exhibited resistance to ampicillin and were fully susceptible to chloramphenicol. The MAR index ranged from 0.13 to 0.50.