Affiliation:
1. Department of Pharmacology, Microbiology and Food Hygiene, The Norwegian School of Veterinary Science,1 and
2. Department of Bacteriology, The National Institute of Public Health,2 Oslo, Norway
Abstract
ABSTRACT
To evaluate the role of seafoods in the epidemiology of human listeriosis and the role of the processing environment as a source of
Listeria monocytogenes
in seafood products, 305
L. monocytogenes
isolates were characterized by multilocus enzyme electrophoresis using 21 genetic loci and restriction enzyme analysis of total DNA. Forty-four isolates were recovered from patients in Norway; 93 were isolated from seafoods, seafood-processing environments, and seawater from 55 different producers; and the remaining 168 isolates originated from six seafood-processing plants and one transport terminal examined in detail for
L. monocytogenes
. The patient isolates fell into 11 electrophoretic types, with four of them being responsible for 77% of the listeriosis cases in 1992 to 1996. Isolates from Norwegian seafoods and processing environments showed great genetic diversity, indicating that seafoods and seafood-processing environments do not offer a niche for specific
L. monocytogenes
strains. On the other hand, isolates from individual processing plants were genetically more homogenous, showing that plants are likely to be colonized with specific subclones of
L. monocytogenes
. The isolation of identical subclones of
L. monocytogenes
from both human patients and seafoods, including ready-to-eat products, suggests that such products may have been possible sources for listeriosis cases in Norway.
Publisher
American Society for Microbiology
Subject
Ecology,Applied Microbiology and Biotechnology,Food Science,Biotechnology