Serovar distribution, virulence gene and antibiotic susceptibility profiling of Salmonella enterica isolated from seafood in Mumbai, India

Abstract

Salmonella contamination of seafood and its environment is an important public health concern. In this study, Salmonella enterica isolated from seafood in Mumbai, India were seroptyped and further characterized with respect to the distribution of virulence genes associated with Salmonella Pathogenicity Islands (SPIs) and their antimicrobial susceptibilities. The study included 89 isolates which were screened for 11 genes associated with five pathogenicity islands (SPI-1 to SPI-5), two phage-encoded virulence genes, and an enterotoxin gene. The isolates were serotyped into 10 serovars namely S. Typhimurium, S. Bareilly, S. Weltevreden, S. Volta, S. Newport, S. Tennessee, S. Kentucky, S. Lindenburg, S. Paratyphi B and S. Alachua. S. Bareilly (33) was the predominant serovar, followed by S. Typhimurium (15), S. Newport (10), S. Kentucky (9), S. Paratyphi B (8), and S. Tennessee (7). Ten S. Typhimurium and one each of S. Kentucky and S. Paratyphi B isolates possessed all the virulence genes tested, while the remaining isolates lacked one or more virulence genes. The antibiotic susceptibility testing revealed that the isolates were resistant against third-generation cephalosporins, quinolones, fluoroquinolones and tetracycline antibiotics, but sensitive to ceftazidime, aztreonam, carbapenems, chloramphenicol, and aminoglycosides. The diverse serovars of Salmonella contaminating fresh seafood in this geographical region constitute a notable public health concern.