RESUMEN
Traditional and regional foods have been increasing in popularity among consumers in Poland for many years. The observed trend of searching for natural and authentic taste encourages many producers to craft products from raw milk, including Korycinski cheeses. The aim of this study was to assess the microbiological hazards resulting from the presence of pathogenic bacteria in Korycinski cheeses available in retail trade. The tests were carried out using accredited methods, including the detection of the presence of Salmonella spp., the enumeration of Listeria monocytogenes, the enumeration of coagulase-positive staphylococci, and the detection of staphylococcal enterotoxins in food when the number of coagulase-positive staphylococci in the sample exceeded the limit of 105 cfu/g. The research material consisted of 45 Korycinski cheeses. The tests conducted revealed that Salmonella spp. was not detected in any of the examined cheeses. However, coagulase-positive staphylococci were present in 68.9% of the samples. In as many as 15 tested cheeses, the level of S. aureus contamination was above 105 cfu/g; therefore, these samples were tested for the presence of staphylococcal enterotoxins. The presence of staphylococcal enterotoxins was found in one Korycinski cheese. In four cheeses, the number of L. monocytogenes exceeded the level of 102 cfu/g, the limit specified in Regulation 2073/2005 on microbiological criteria for foodstuffs. The obtained research results confirm the validity of monitoring the microbiological quality of Korycinski cheeses and the need to increase awareness of ensuring proper hygienic conditions of production, including the increased risk associated with unpasteurized milk products.
RESUMEN
The study describes the characterization of Listeria monocytogenes isolated from the general 2017-2019 national official control and monitoring sampling program. A total of 60,928 of ready-to-eat (RTE) food products were collected in retail in Poland, while the number of L. monocytogenes contaminated samples was 67 (0.1%). The majority of the strains belonged to molecular serotype IVb followed by IIa, frequently associated with human listeriosis. Furthermore, 61.2% of the isolates were resistant at least to one of the tested antimicrobials: penicillin, ampicillin, meropenem, erythromycin, sulfamethoxazole-trimethoprim, amoxicillin-clavulanic acid, ciprofloxacin, chloramphenicol, gentamicin, vancomycin, tetracycline and rifampicin. Virulence genes inlA, inlC, inlJ and lmo2672 were detected in all of the isolates. In our study the llsX gene (encoding LLS) exhibited 11.6% positivity. The 32 strains were grouped into 12 clonal complexes (CCs) which belong to the major clones that are in circulation in Europe. Among them, seven strains with the cgMLST close relatedness (CC2) were isolated from diverse food sectors, underlining a large circulation of this clone in Poland, most likely from multiple introduction sources. Additionally, two RTE strains CC6 and one CC37 were identified as closely related by cgMLST to two publicly available genomes of clinical strains isolated in Poland in 2012-2013. These results indicate the large strain circulation and point to RTE food products as a potential source of human listeriosis. The present study provided data to capture the contamination status of L. monocytogenes in foods at the retail level in Poland and assess the potential risk of this pathogen for human safety.
