Isolation, Genotyping and Antibiogram Profile of Clostridium perfringens Isolates Recovered from Freshwater Fish and Fish Products from Kolkata Region.

The present study reports the isolation of Clostridium perfringens from samples comprising of freshwater fish and fish products from Kolkata city of India, and determining their genotypes and antibiogram profile. A total of 102 samples consisting of intestinal and gill samples from fresh water fish (n=69) and fish products including fish pickles, fish curry and fried fish (n=33) were collected randomly from retail shops and restaurants. On cultural isolation and biochemical characterization, 24 (23.52%) samples [17 (24.63%) from fresh water fish (n=69) and 07 (21.21%) from fish products (n=33)] were presumptively identified as C. perfringens positive. The genotyping of the recovered C. perfringens isolates was done by amplifying species specific 16S rRNA gene and four major lethal toxin genes viz., alpha toxin gene (cpa), beta toxin gene (cpb), epsilon toxin gene (εtx) and iota toxin gene (ιtx). Apart from these, enterotoxin gene (cpe) and beta2 toxin gene (cpb2) were also targeted. In PCR assays, all the 24 (100%) isolates [17 (70.83%) from fresh water fish and 07 (29.17%) from fish products] were found to harbor species specific 16S rRNA and cpa toxin gene, however, 17 (70.83%) cpa positive isolates [12 (70.58%) from fresh water fish and 05 (71.42%) from fish products] were also found to harbor additional cpb2 toxin gene, while none of the isolates were found to be positive for cpb, εtx, ιtx and cpe genes. Based on these results, all the isolates were confirmed as C. perfringens type A (containing only alpha toxin gene). On antibiotic sensitivity testing, 76.47% of the isolates were found to be multidrug resistant with ciprofloxacin and amoxicillin/clavulanic acid as being the most sensitive drugs. Report regarding isolation and molecular characterization of C. perfringens from fish and fish products especially from Kolkata does not exist as well as from other regions of India are very scanty. The present findings suggest that fish may be considered as a potential source of C. perfringens type A infection to human populations through food chain and the high antibiotic resistance observed may pose serious public health concerns. Further detailed molecular epidemiological and antibiogram studies are suggested for designing and adapting appropriate prevention and control strategies for countering this important pathogen and its food-borne zoonotic concerns. [ABSTRACT FROM AUTHOR]