Abstract
Altogether 150 samples of vacuum-packed fish were examined for the presence of Listeria species. Listeria monocytogenes were isolated from 12 of 58 'gravad' fish samples, 3 of 26 cold-smoked and one of 66 hot-smoked fish samples. Ten of these 16 positive samples harboured more than 100 L. monocytogenes cfu/g. The highest level (132,000) was found in a sample of hot-smoked rainbow trout (Oncorhynchus mykiss). Serogroup 1/2 was most frequently found, followed by 4 and 3. One sample of gravad rainbow trout harboured more than one serogroup of L. monocytogenes. L. innocua and L. seeligeri were isolated from 12 and 1 samples, respectively.