The Objective of This Study Was to Isolation and Characterization of Listeria Species and Determines Listeria Monocytogenes Serotypes in Fresh Fish, Shrimp, Crab and Lobster in Isfahan and Shahrekord, Iran

The objective of this study was to isolation and characterization of Listeria species and determines Listeria monocytogenes serotypes in fresh fish, shrimp, crab and lobster in Isfahan and Shahrekord, Iran. From September 2010 to April 2011, a total of 300 samples of fresh fish, shrimp, crab and lobster were obtained from randomly selected retail stores in Isfahan and Shahrekord, Iran. The samples were tested for the presence of Listeria species using a ISO 11290 protocol and then only Listeria monocytogenes isolates identified by bacteriological methods were tested by polymerase chain reaction (PCR) for serotypes detection and presences of virulence associated genes. From the total 300 samples, 23 (10.45%) fresh fish and 1 (2.5%) shrimp samples were positive for Listeria spp., but none of the lobster and crab samples were positive for Listeria species. Listeria monocytogenes only isolated from 17 fish (7.25%) and 1 shrimp (2.5%) samples while L. innocua, L. ivanovii and L. seeligeri only detected in fish samples (2 (0.9%), 3 (1.36%) and 1 (0.45%)), respectively. All of 18 isolates of L. monocytogenes showed the characteristic enhancement of hemolytic zone with S. aureus. From these positive L. monocytogenes, 66.66%, 5.55% and 27.77% had 4b, 1/2a and 1/2b serotypes, respectively. Consumption of these sea foods, either raw or undercooked, may contribute to food-borne illness due to L. monocytogenes in Iran. Also, L. monocytogenes in raw seafood may pose a health risk in kitchens if contaminating ready-to-eat food