Occurrence of Listeria in hot and cold smoked seafood products

Over a one-year period, 258 samples of smoked fish products were obtained from retail outlets in Newfoundland and processed for Listeria. Of these, 142 were hot smoked and 116 cold smoked, and the samples comprised of nine species of fish. The Canadian FDA listeria isolation protocol consisted of a two-stage enrichment followed by plating on selective isolation media, Oxford, and LPM. An additional selective medium, PALCAM, was also used. Listeria spp. were isolated from 43 of 258 (16.7%) samples processed in all, with hot smoked products yielding 25.4% (36/142) of the isolates, and cold smoked products yielding 6% of the isolates (7/116). Among the nine species tested, cod had the highest rate of Listeria contamination at 46.7%. Of the 43 Listeria spp. isolated, 18 (41.9%) were L. innocua, 13 (30.2%) were L. welshimeri and 12 (27.9%) were L. monocytogenes.