Analysis of antimicrobial resistance and plasmid profiles in Salmonella serovars associated with tropical seafood of India

Abstract

A total of 256 Salmonella strains consisting of 29 Salmonella serovars isolated from seafood of Cochin (India) were analyzed for resistance to antimicrobials commonly used in human and veterinary medicines as therapeutic agents. The 10 most predominant Salmonella serovars in seafood were also characterized for presence of plasmids using the alkaline lysis method. Antimicrobial susceptibility studies highlighted a comparatively high resistance in Salmonella isolates to sulfamethizol and carbenicillin, and moderate resistance to nalidixic acid and oxytetracycline. Nevertheless, antimicrobial resistance was not observed against ampicillin, ciprofloxacin, chloramphenicol, gentamicin, and kanamycin in different Salmonella serovars. Fifty percent of the Salmonella isolates, comprising 16 Salmonella serovars, were resistant to sulfamethizol followed by 39% resistant to carbenicillin and 14% resistant to oxytetracycline. Multidrug resistance was detected in 39.4%, 14.4%, 12.1%, and 1.5% of Salmonella isolates towards two drugs (sulfamethizol and carbenicillin), three drugs (sulfamethizol, carbenicillin, and oxytetracycline), four drugs (sulfamethizol, carbenicillin, oxytetracycline, and nalidixic acid), and five drugs (sulfamethizol, carbenicillin, oxytetracycline, nalidixic acid, and streptomycin), respectively. Plasmid profiling highlighted the presence of nine plasmid profiles in Salmonella serovars and plasmids that were not detected in Salmonella enterica subsp. enterica Weltevreden, Salmonella Rissen, Salmonella Bareilly, Salmonella Irumu, Salmonella Ohio, Salmonella Oslo, and Salmonella Typhi isolated from seafood.