Isolation and confirmation of Listeria species from seafood off Goa region by polymerase chain reaction

Abstract

Several food borne outbreaks have highlighted the importance of Listeria monocytogenes to the public health and have been recognized as an emerging, important food borne pathogen, and a causative agent of listerioses. A number of genes are involved in the manifestation of Listeria virulence, hlyA is one among them. 111 marine fish samples including prawns, finfishes and bivalves were screened for the presence of Listeria species. The isolates were characterized biochemically and further L. monocytogenes were confirmed by polymerase chain reaction (PCR) technique using the hlyA gene as a tool to differentiate between L. monocytogenes and other non-pathogenic Listeria species. Out of 111 samples 5(4.5 percent) samples were positive for L. monocytogenes. Among the three different types of samples bivalves were found to have maximum percent (12.5) of L. monocytogenes followed by prawns (3.84) and finfishes (2.9). Among all the 111 samples, 15(13.51 percent) samples were positive for other Listeria species. It was observed that Listeria occurrence is more in shellfishes than in fin fishes. All the isolates were sensitive towards five different antibiotics in sequence ciprofloxacin more than sulphafurazole more than norfloxacin more than ampicillin and gentamicin.