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Listeria monocytogenesis 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. monocytogenesin 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. monocytogenesisolates 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. monocytogenesisolates harbored the virulence-associated genes inlA, inlC, inlJ,and lmo2672. The llsXmarker 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. monocytogenesisolates. A low incidence of resistance to amoxicillin–clavulanic acid (6% of isolates) was also detected. All L. monocytogenesisolates 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.

The prevalence, count and molecular identification of Campylobacterspp. in Polish poultry meat were analysed. 181 samples of meat from chicken (70), turkey (47), duck (54) and goose (10) were studied. Campylobacterspp. was found in 64% of meat samples. The highest prevalence of this pathogen was detected for duck meat. On average 80% of duck samples were contaminated with Campylobacterspp. The counts of Campylobacterspp. in positive samples remained under ten colony forming units per gram of product in 59% of poultry meat. C. jejuniwas more frequently detected in poultry meat than C. coli.

AbstractThe aim of this study was to investigate the mechanism of rifampicin resistance in Listeria monocytogenesstrains isolated from different types of food and the impact of specific mutations in the rpoBgene on susceptibility to different antimicrobial agents and on fitness cost. Fifteen spontaneous rifampicin-resistant strains were selected. The DNA regions corresponding to clusters I–II, III, and N-terminal end of the rpoBgene of Escherichia coliwere amplified and sequenced, leading to the identification of 10 different substitutions, nine of which (Ser466Pro, Gln470Lys Asp473Asn, Gly479Asp, His483Tyr/Arg/Asp, Arg486His, and Leu490Pro) were located in cluster I and one (Pro521Leu) in cluster II. From among these mutations, substitutions at positions 466, 470, 486, 490, and 521 have not been described for L. monocytogenes.Only substitutions at positions 470, 479, 483, and 486 lead to resistance to very high concentrations of rifampicin (minimum inhibitory concentration [MIC] ≥256 μg/mL) and rifabutin (MIC 128 μg/mL). Furthermore, mutations at positions 473, 490, and 521 had different effects on susceptibility to rifampicin compared to other bacterial species. A correlation between rifampicin resistance and susceptibility to a wide range of antimicrobials was determined. Substitutions in RpoB did not change the susceptibility of the mutants to different antimicrobials. The fitness of the mutants was assessed by paired competition experiments. Mutations at positions 470 and 479 were not associated with a reduction in fitness level. There was no correlation between the MIC of rifampicin and fitness cost. The risk of transmission of resistant strains through the food chain highlights the need for monitoring resistance, identifying mutant organisms, their genotypes, and their altered phenotypes to understand their dissemination.

The purpose of the present study was to determine the prevalence of thermophilic Campylobacterin poultry, pork, and beef meat at the retail level and to identify the main categories of meat representing the most significant reservoirs of Campylobacter.A monitoring study was conducted throughout Poland from 2009 to 2013. A total of 1,700 fresh meat samples were collected from supermarkets, large retail outlets, and smaller stores. Thermophilic Campylobacterspecies were detected in 690 (49.3%) of 1,400 poultry samples collected from retail trade. Strains were isolated from 50.2 and 41.1% of raw chicken and turkey meat samples, respectively, and from 50.1 and 42.6% of raw chicken and turkey giblets. The incidence of Campylobacterspp. on pork (10.6%) and beef (10.1%) was significantly lower than on poultry. Campylobacter jejuniwas the most prevalent Campylobacterspecies in chicken (46.6%), pork (68.6%), and beef (66.7%), and Campylobacter coliwas the most frequently isolated Campylobacterspecies in turkey meat (71.2%). This study revealed that retail raw meats are often contaminated with Campylobacter; however, the prevalence of these pathogens is markedly different in different meats. Raw retail meats are potential vehicles for transmitting foodborne diseases, and our findings stress the need for increased implementation of hazard analysis critical control point programs and consumer food safety education efforts.