Prevalence and characterisation of Listeria spp. from seafood

Abstract

Listeria monocytogenes, the causative organism of listeriosis, is primarily transmitted to humans through contaminated food. We examined the prevalence of L. monocytogenes isolates from fishery products marketed in Goa, India. A total of 221 raw seafood samples were examined for the presence of Listeria species following ISO 11290 protocol. Thirty seven (16.74%) samples were positive for Listeria species. Out of these, isolates from 4 (1.8%) samples were confirmed as L. monocytogenes, the remaining 33 isolates were Listeria innocua. All the isolates were subjected to PCR for the hlyA gene, which was detected in all the L. monocytogenes isolates. The isolates were also found to express phosphatidyl-inositol specific phospholipase C activity on ALOA agar. Multiplex PCR-based clonal typing revealed three L. monocytogenes isolates to be of serovar group 1/2a, 1/2c, 3a, 3c while the remaining isolates belonged to serovar group 1/2b, 3b 4b, 4d and 4e. The isolates were grouped into two AscI and ApaI PFGE (pulsed field gel electrophoresis) profiles. Prevalence of
L. monocytogenes in fresh seafood is of significance as it may contaminate and persist in the processing environment.