Prevalence of Listeria spp. in freshwater fish (Oncorhynchus mykiss and Carassius gibelio) and the environment of fish markets in Northern Greece

In this study, a total of 405 samples from freshwater fish, personnel and environment were collected from retail fish markets in three cities in Northern Greece and they were examined for the presence of Listeria spp. They consisted of 136 samples from the skin and 136 from the flesh of 71 rainbow trout (Oncorhynchus mykiss) and 65 gibel carps (Carassius gibelio), 20 from workers' hands, 27 from workers' knives, 22 from working surfaces, 29 from wooden boxes, 15 from plastic boxes, 18 from floor surfaces and 2 from drainage lids. Listeria spp. was isolated from 10.62% of the samples, L. rnonocytogenes were 0.99%, 4.69% L. seeligeri and 4.94% L. innocua, respectively. L. monocytogenes was isolated from 3.54% of the environmental samples and none from fresh water fish and workers hands' samples. Listeria spp. was isolated from 1.54% of gibel carp flesh (1.54% L. seeligeri), from 18.46% of gibel carp skin (10.77% L. seeligeri and 7.69% L. innocua) and from 8.45% from rainbow trout skin samples (1.41% L. seeligeri and 7.04% L. innocua). The higher rate of isolation of Listeria spp. from the environmental samples emphasises the importance of sanitary conditions in order to reduce the risk of contamination by L. monocytogenes at the retail level.