Occurrence of listeria monocytogenes in some marine fresh and frozen fish marketed in Damietta, Egypt

The objectives of this study were to determine the incidence of Listeria spp. and Listeria monocytogenes isolated from two types of imported frozen and fresh locally marine fish samples obtained from fish markets in Damietta, Egypt. A total of 400 fish samples, comprising 100 samples each of fresh Saurus, fresh Sardines, frozen Saurus and frozen Sardines, were collected from different public fish markets at Damietta Governorate. Listeria isolation was performed according to FDA, (2011) protocols. Standard microbiological techniques were confirmed to L. monocytogenes by PCRAmplification of a fragment of hyla gene. The present data revealed that the overall incidence of Listeria spp. in was (13.75%), whereas the overall incidence of L. monocytogenes was (4.5%). Listeria spp. were isolated from fresh Saurus fish, fresh Sardines, frozen Saurus and frozen Sardines as 25(25%), 16(16%), 8(8%), 6(6%), respectively. The highest prevalence (25%) of Listeria spp. were observed in fresh Saurus, while the lowest prevalence was detected in frozen Sardines (6%). Ten isolates (10%) from fresh Saurus fish samples were confirmed to L. monocytogenes, while L. Monocytogenes was not isolated from frozen Sardines. The highest incidence of L. monocytogenes was in Kafr Saad 7/128 (5.4%) and Damietta city 9/44 (5.11%). Serovar determination of L. monocytogenes18 isolates revealed that the serovar 1/2a was the predominant L. monocytogenes serovar in the samples tested in the present study. It was isolated from the examined fresh fish and frozen Saurus while Serovar 1/2c was isolated from fresh Sardine only and Serovar 4b was isolated from fresh Saurus only. In conclusion, this study showed that L.monocytogenes were common contaminant of fish obtained from Damietta fish markets, and this may pose serious public health implications.