Detection and characterization of virulence factors in lactose positive and lactose negative Salmonella serovars isolated from seafood

This study is aimed to understand the prevalence of lactose positive (lac+) and lactose negative (lac−) Salmonella serovars in seafood and to determine the presence of virulence traits by PCR assay. Salmonella serovars were isolated from fish, shrimp, crab, clam, mussel, oyster, squid and cuttlefish of fish market and fish landing centers of Cochin, India. Lac− Salmonella were identified in 18.9% of seafood samples, whereas, 2% of seafood samples harboured lac+ Salmonella. The virulence factors in lac+ and lac− Salmonella were characterized by amplification of three virulence genes i.e. invA, stn and fimA genes. Results exhibited that except fim A gene in Salmonella IIIa isolates, all other lac+ and lac− Salmonella serovars showed the presence of invA, stn and fimA genes. Thus, study highlighted the prevalence of virulent lac+ and lac− Salmonella serovars in seafood.