1992 Volume 9 Issue 3 Pages 165-170
From May, 1991 to February, 1992, a total of 909 samples of seafoods and seafood products in Tokyo Metropolitan Central Wholesale Market, Tsukiji Market were examined for the presence of Listeria monocytogenes and other Listeria spp. by the combined use of Listeria selective agar (Oxford formulation: Oxoid) and Palcam-Listeria-Selective agar (Merck) after enrichment culture in UVM modified Listeria enrichment broth (Difco). The overall incidence of Listeria spp. was found to be 9.0% in raw seafoods (except shellfish), 9.8% in raw shellfish, 25.0% in boiled shellfish and 14.1% in seafood products.
It was revealed that 1.8% of 16 isolates were identified as L. monocytogenes, 7.8% as L. innocua, 1.5% as L. welshimeri, 0.7% as L. seeligeri and 0.4% as L. ivanovii. L. monocytogenes was isolated from smoked salmon (26.7%), salmon flakes (12.5%), crab-meat flakes (8.3%), boiled egg cockles (5.6%), sea urchin roes (3.6%), pink prawns (2.5%) and suquillas, boiled and peeled (2.4%). The predominant serotype of 16 isolates of L. monocytogenes were 1/2a and 1/2b.
Most of the seafoods and seafood products contaminated with Listeria spp. found in this study were processed and packed in manufacturing processing.
