Prevalence and characterization of Salmonella and Listeria monocytogenes in french raw pork meat at the distribution level

Abstract

This study was undertaken in 2010 to estimate the occurrence of Listeria monocytogenes in raw pork meat at the distribution level in France. A total of 320 samples (minced pork meat, pork chop, fillet and roast, and other various pieces) have been collected at the distribution level in various geographical areas throughout France. Sampling was done over the year. Detection and enumeration were conducted as described in ISO methods. All isolates were serogrouped by PCR and genotyped by a standardized PFGE method. L. monocytogenes was detected in 12.8% of the samples (41 on 320). Eight samples could be numerated and number of ufc/g varied from 10 to 730. Minced pork meats were particularly contaminated (25%). The 159 isolates of L. monocytogenes were serogrouped by PCR; 57, 11, 75, 16 isolates were respectively from serogroup IIa, IIb, IIc and IV. PFGE, after ApaI and AscI restriction, generated 33 and 23 PFGE types respectively. Most often, isolates of L. monocytogenes from a same sample highlighted the same serogroup and the same PFGE pattern except one sample from which the 8 isolates were distributed in 3 serogroups and 5 PFGE patterns. Diversity of genotypes was higher among isolates from minced meat with 20 combined profiles. Few genotypes were common between minced meats, cut meats and others pieces. This study provided recent valuable information on the occurrence of L. monocytogenes (13.3%) in raw pork meat at the distribution level. Minced pork meats were particularly contaminated and various genotypes of L. monocytogenes were found indicating that various source of meats and transformation of meat increase the risk to contaminate minced pork meat.