Phenotypic And Genotypic characterization of Vibrio cholerae Associated with Fresh seafood from the Major Markets of Cochin,India

Abstract- As the causative agent of cholera, Vibrio cholerae represents a significant threat to human health especially in developing countries around the world. This pathogen also forms biofilms which favors its attachment to surfaces and survival to hostile environment and thus acquire drug resistance mechanism. Hence, this study aimed to investigate the occurrence of V. cholerae in seafood and to determine the antimicrobial susceptibility patterns and biofilm forming capacity.

In this study, 22 V. cholerae isolates were obtained from 43 seafood samples and were biochemically confirmed. PCR was employed to differentiate the isolates between toxigenic strain targeting ctx gene and non-toxigenic strain targeting ompU gene by using gene specific primers. None of the isolates showed positive for ctx gene whereas 2 isolates (VCS4 and VCC3) showed positive bands for ompU gene. The antibiotic susceptibility test against 16 antibiotics showed that all the isolates were exhibited resistance against nalidixic acid, trimethoprim, erythromycin, streptomycin and ciprofloxacin whereas, sensitive against norfloxacin, polymixin B and azithromycin. However, there is a fluctuation in the resistance pattern for the rest of the antibiotics viz., doxycycline, Amikacin, chloramphenicol, tetracycline, amoxycilin, Nitrofurantoin and gentamicin. Some strains showed resistant, while some showed intermediately resistant or sensitive. The MAR index for all the isolates was above 0.2 ranging between 0.4 and 0.6. The MIC analysis showed that all the isolates exhibited complete resistance with no MIC level against chloramphenicol, trimethoprim and nalidixic acid. The lowest MIC values obtained was 0.023 mcg/ml exhibited by 4 (18%) isolates against ciprofloxacin whereas, the highest was found to be 96 mcg/ml shown by 12 (55%) isolates against nitrofurantoin. The evaluation of biofilm by conventional tube method resulted 4 isolates (18%) as strong biofilm producers and 10 (46%) as moderate biofilm producers. The remaining 36% were weak biofilm formers or it can be assumed as non-biofilm producers. Interestingly this study revealed the emergence of antibiotic resistance in biofilm forming V.cholerae seen associated with seafood from Cochin markets, which may pose future threat to develop control strategies in the fish processing industry and also pose significant treatment challenge to physicians.