ABSTRACT

Listeria monocytogenes is a potential hazard for food safety and therefore for 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 for retail sale. Among the 184,439 food samples collected within the framework of a 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 noncompliant samples. Seventy L. monocytogenes isolates from these 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 12 (17%) of the 70 isolates. Ampicillin resistance was the most common resistance phenotype and was identified in 83% of the L. monocytogenes isolates. A low incidence of resistance to amoxicillin–clavulanic acid (6% of 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 risks.

HIGHLIGHTS
  • L. monocytogenes was isolated from 0.3% of all food samples.

  • RTE meat products accounted for 40% of noncompliant food samples.

  • Among 70 L. monocytogenes isolates, serogroup IIa (1/2a-3a) was the most prevalent (53%).

  • Genes inlA, inlC, and lmo2672 were found in all isolates, and gene llsX was found in 17%.

  • Resistance to ampicillin was the most type of antibiotic resistance (83%) among the strains.

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