Occurrence and characteristics of Listeria monocytogenes in ready-to-eat meat products in Poland

Listeria monocytogenes is a potential hazard for food safety and therefore public health. The aim of the present study was to determine the prevalence and characteristics of L. monocytogenes in Polish ready-to-eat (RTE) meat products in retail. Among the 184 439 food samples collected within the framework of national official control and monitoring program only 0.3% were positive for L. monocytogenes. A significant group of products that did not meet the criteria were RTE meat products. This group accounted for 40% of all non compliant samples. A total of 70 L. monocytogenes isolates from RTE meat products (meat, sausages and delicatessen products with meat) were examined. The majority of the tested isolates (51%) belonged to serogroup 1/2a-3a, followed by 1/2c-3c (21%), 1/2b-3b-7 (14%) and 4ab-4b-4d-4e (13%). Serogroup 4a-4c was not present among the tested isolates. All L. monocytogenes isolates harbored the virulence-associated genes inlA, inlC, inlJ and lmo2672 . The llsX marker was detected in twelve of 70 (17%) isolates. Ampicillin resistance was the most common resistance phenotype and was identified in 83% of L. monocytogenes isolates. A low incidence of resistance to amoxicillin/clavunate acid (6% isolates) was also detected. All L. monocytogenes isolates were susceptible to chloramphenicol, gentamicin, ciprofloxacin, meropenem, sulfamethoxazole-trimethoprim, tetracycline and erythromycin. This work provides useful information regarding contamination of RTE meat products with L. monocytogenes, which may have implications for food safety risk.