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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. [ABSTRACT FROM AUTHOR]

Abstract The sixty-seven nonpathogenic Listeria spp. strains isolated from food and food processing environments in Poland were examined for the presence of benzalkonium chloride (BC) resistance cassette (bcrABC) and four different variants of cadmium resistance determinants (cadA1-cadA4). All the strains were phenotypically resistant to cadmium and 22 among them were also resistant to BC. PCR-based analysis revealed that bcrABC cassette was harbored by 95.5% of the strains phenotypically resistant to BC. All of them harbored also either cadA1 or cadA2 genes (none carried cadA3 or cadA4), which corresponded to the presence of plasmids with two restriction patterns. The strains resistant to cadmium but susceptible to BC harbored only the cadA1 gene variant. DNA-DNA hybridization analysis showed that all the identified bcrABC , cadA 1 and cadA2 genes were located within plasmids, classified into 11 groups of RFLP profiles. Only one of the plasmids – pLIS1 of Listeria welshimeri (carrying bcrABC and cadA2) – was capable of efficient conjugal transfer from nonpathogenic Listeria isolates to a pathogenic Listeria monocytogenes strain. Analysis of the complete nucleotide sequence of pLIS1 (the first sequenced plasmid of L. welshimeri species) revealed the presence of genes involved in plasmid replication, stabilization and transfer as well as genes conferring resistance phenotypes. Comparative analysis showed that pLIS1 genome is highly similar to a group of plasmids originating from L. monocytogenes strains. A common feature of pLIS1 and its relatives, besides the presence of the resistance genes, is the presence of numerous transposable elements (TEs). The analysis revealed the important role of TEs in both promoting genetic rearrangements within Listeria spp. plasmids and the acquisition of resistance determinants. Highlights • Nonpathogenic cadmium resistant Listeria spp. carry either cadA1 or cadA2 genes • Majority of strains resistant to benzalkonium chloride carry bcrABC genes • The resistance determinants are located within plasmids of 11 RFLP patterns • Plasmid pLIS1 of L. welshimeri is capable of efficient conjugal transfer • pLIS1 contains bcrABC and cadA2 as well as numerous transposable elements [ABSTRACT FROM AUTHOR]

A total of 127 Listeria isolates from food and food processing environments, including 75 L. innocua , 49 L. welshimeri , 2 L. seeligeri and 1 L. grayi were tested for susceptibility to eight antimicrobials, benzalkonium chloride (BC), cadmium and arsenic. The isolates were also screened for the presence of extrachromosomal genetic elements - plasmids, and their restriction pattern types were determined. All strains were susceptible to ampicillin, ciprofloxacin, erythromycin, gentamicin, rifampicin, trimethoprim and vancomycin. Two of the L. innocua isolates showed resistance to tetracycline and minocycline. The resistance was determined by the presence of chromosomal localization of tet (M) gene, which was not integrated in the transposon Tn 916 -Tn 1545 family. Of analyzed isolates, 18.11% and 55.91% isolates were resistant to BC and cadmium, respectively, but all were susceptible to arsenic. Resistance to BC was correlated with resistance to cadmium - all BC resistant isolates were also resistant to cadmium. On the other hand, 67.61% of cadmium-resistant isolates were susceptible to BC, suggesting that cadmium and BC resistance were not always concurrent in Listeria species. 48.03% of isolates contained plasmids. The size of most of the identified replicons was in the range of 50–90 kb. All plasmids were classified into 12 groups with identical restriction pattern (I–XII). Interestingly, plasmids belonging to the same group were determined in isolates of the same species. Only in one case, plasmids with I-type profile were identified in L. innocua and L. welshimeri. There was an association between resistance to BC and plasmid DNA presence: all resistant isolates carried a plasmid. A correlation between resistance to cadmium and plasmid carriage was also observed in L. innocua and L. seeligeri isolates, but among resistant L. welshimeri, 23.08% of isolates did not have plasmids. This may suggest that resistance is associated with determinants located within the chromosome. To elucidate the adaptation strategies and ecology of Listeria spp., it is important to have a better understanding of its resistance to antimicrobials and environmental toxicants such as heavy metals and disinfectants. [ABSTRACT FROM AUTHOR]

The purpose of the present study was to determine the prevalence of thermophilic Campylobacter in 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 Campylobacter species 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 Campylobacter spp. on pork ( 10.6%) and beef ( 10.1 %) was significantly lower than on poultry. Campylobacter jejuni was the most prevalent Campylobacter species in chicken (46.6%), pork (68.6%), and beef (66.7%), and Campylobacter coli was the most frequently isolated Campylobacter species 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. [ABSTRACT FROM AUTHOR]

Abstract: A total of 471 Listeria monocytogenes isolates from different types of food and food-related sources in Poland during 2004–2010 were examined. This number includes 200 isolates from fish, 144 from fresh and frozen vegetables, 43 ready-to-eat products (deli foods, cold cuts), 13 from dairy products, 16 from raw meats, 15 from confectionery products and 40 directly from processing plants. All isolates were subjected to serotyping and lineage assays using PCR, and antimicrobial susceptibility using E-test and a broth microdilution method. Of all isolates, 256 (54.4%), 120 (25.5%), 59 (12.5%), 36 (7.6%) were identified as serotypes 1/2a (or 3a), 1/2c (or 3c), 1/2b (or 3b or 7), and 4b (or 4d or 4e), respectively. A direct correlation between the most common serotypes and three L. monocytogenes lineages was also observed. All L. monocytogenes isolates belonged to lineages I (20.2%) and II (79.8%). All strains were sensitive to ampicillin, amoxicillin, gentamicin, erythromycin, trimethoprim, rifampicin, vancomycin, chloramphenicol and sulfamethoxazol. Two of the L. monocytogenes strains (0.42%) showed phenotypic resistance. One strain was resistant to tetracycline and minocycline due to the presence of tet(M). It did not carry gene int, which may indicate that the tet(M) gene in this strain was not integrated in the transposon Tn916-Tn1545 family. The resistance of the second strain to ciprofloxacin and norfloxacin was attributed to active efflux associated with overexpression of gene lde. Our data indicate the low prevalence of antimicrobial resistance among L. monocytogenes isolates from food and food-related sources in Poland. [Copyright &y& Elsevier]

Abstract: This study presents the results of investigations on the susceptibility of Campylobacter spp. strains isolated from chicken meat and giblets to fluorochinolones (ciprofloxacin), macrolides (erythromycin), tetracyclines (tetracycline) and aminoglycosides (gentamicin) andV an analysis of the molecular mechanisms of resistance to the selected antibiotics. Between January 2008 and December 2009 a total of 218 samples of chicken meat and giblets from retail trade in Poland were examined. Campylobacter bacteria were found in 143 samples, that is in 65.6% of the total number embraced by the study. Campylobacter coli was the most ubiquitous – its presence was determined in 108 samples out of 143 (75.5%), whereas Campylobacter jejuni was found in 35 of the contaminated samples (24.5%). The results obtained point to the high percentage (97.9%) of Campylobacter isolates resistant to ciprofloxacin. 92 strains (64.3%) were resistant to tetracycline, 14 (9.1%) to erythromycin and only 9 (6.3%) to gentamicin. Moreover, ten out of the 143 resistant Campylobacter strains (7.0%) were found to be resistant to at least three unrelated antibiotics. [Copyright &y& Elsevier]

In 2007 and 2008, a monitoring study was carried out in Poland to examine the occurrence of thermotolerant Campylobacter spp. in raw and cooked chicken products available on the retail market. A total of 912 samples were tested: 443 samples of raw chicken meat, 146 samples of giblets, and 323 ready-to-eat poultry products (150 samples of spit-roasted chicken, 56 samples of smoked chicken, and 117 samples of pâté and cold meats). A high level of contamination of raw chicken meat (51.7% o samples) and chicken giblets (47.3% of samples) was detected. However, thermotolerant Campylobacter spp. were found in only 1.2% of the ready-to-eat poultry products. [ABSTRACT FROM AUTHOR]

[Display omitted] • The concept of bioanalytical insight into the life of microbial populations is presented. • The flow analysis system operating as a real-time on-line monitor of biocatalytic activity is developed. • The developed MCFA monitor is useful for investigations on urease-positive bacteria growth. • Advantages of chemical monitoring and modelling of microbial growth are announced. In this publication an alternative approach to investigations of bacterial growth is proposed. Contrary to the conventional physical methods it is based on enzyme activity detection. The procedure for real-time and on-line monitoring of microbial ureolytic activity (applied as a model experimental biosystem) in the flow analysis format is presented. The developed fully-mechanized bioanalytical flow system is composed of solenoid micropumps and microvalves actuated by Arduino microcontroller. The photometric detection based on Nessler reaction is performed using dedicated flow-through optoelectronic detector made of paired light emitting diodes. The developed bioanalytical system allows discrete assaying of microbial urease in the wide range of activity up to 5.4 U mL−1 with detection limit below 0.44 U mL−1, a high sensitivity in the linear range of response (up to 200 mV U−1 mL and relatively high throughput (9 detection per hour). The proposed differential procedure of measurements (i.e. a difference between peaks register for sample with and without external addition of urea is treated as an analytical signal) allows elimination of interfering effects from substrate and products of biocatalysed reaction as well as other components of medium used for microbial growth. The developed bioanalytical system was successfully applied for the control of growth of urease-positive bacteria strains (Proteus vulgaris , Klebsiella pneumoniae and Paracoccus yeei) including examination of effects from various microbial cultivation conditions like temperature, composition of culture medium and amount of substrate required for induction of bacterial enzymatic activity. The developed bioanalytical flow system can be applied for metabolic activity-based estimation of parameters of lag and log phases of microbial growth as well as for detection of decline phase. [ABSTRACT FROM AUTHOR]

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. • L. monocytogenes was isolated from 0.1% of the RTE food samples. • The most frequently identified molecular serogroups were IVb (51%) and IIa (42%). • 48% strains belonged to the major clonal complexes (CCs) circulating in Europe. • Seven strains (CC2) close relatedness were isolated from diverse food sectors. • Two strains CC6 and one C37 were closely related to clinical strains in Poland. [ABSTRACT FROM AUTHOR]

Campylobacter-associated gastroenteritis remains an important cause of morbidity worldwide, and some evidence suggests that poultry is an important source of this foodborne infection in humans. This study was conducted to analyze the prevalence and genetic background of resistance of 149 Campylobacterjejuni and 54 Campylobacter coli strains isolated from broiler chicken carcasses and from stool samples of infected children in Poland from 2003 through 2005. Nearly all isolates were susceptible to macrolides and aminoglycosides. The highest resistance in both human and chicken strains was observed for ciprofloxacin (more than 40%), followed by ampicillin (13 to 21%), and tetracycline (8 to 29%). Resistance to ampicillin and tetracycline rose significantly between 2003 and 2005. Slight differences in resistance between human and chicken isolates indicate that although chicken meat is not the only source of Campylobacter infection in our population, it can be involved in the transmission of drug-resistant Campylobacter strains to humans. [ABSTRACT FROM AUTHOR]

The aim of the present study is to investigate the prevalence and genetic diversity of Listeria monocytogenes in various fresh and frozen vegetable products available in Poland. The samples were collected at retail market within the framework of national official control and monitoring program. In the years 2016–2019 a total of 49 samples out of 8712 collected vegetable samples were positive for L. monocytogenes. Our findings demonstrated that the occurrence of L. monocytogenes in various vegetable products was generally low, on average only 0.56% in the studied years. All isolates were susceptible to 11 antimicrobial agents: penicillin, ampicillin, meropenem, erythromycin, sulfamethoxazole-trimethoprim, amoxicillin-clavulanic acid, ciprofloxacin, chloramphenicol, gentamicin, vancomycin, and tetracycline. All of them harbored virulence-associated genes (inlA , inlC , and lmo2672), 82% harbored inlJ gene and few of them (22%) also possessed the llsX gene. The majority of collected isolates (65%) belonged to molecular serogroup 1/2a-3a, followed by 4ab-4b-4d-4e (33%), and only one to serogroup 1/2b-3b-7 (2%). Isolates yielded 18 different restriction profiles, revealing a large cluster of contamination linked to frozen corn (21 strains) and distributed in 3 pulsotypes. MLST analysis classified selected isolates into nine clonal complexes (CCs). The obtained results contribute to characterizing the diversity of L. monocytogenes isolated from various vegetable products in Poland and their impact on food safety and public health. • 0.56% vegetable products in Poland were positive for L. monocytogenes. • The most prevalent was serogroup 1/2a-3a (65%). • All isolates were susceptible to tested antimicrobials. • The inlA , inlC and lmo2672 genes were observed in all isolates. • MLST analysis classified selected isolates into nine clonal complexes. [ABSTRACT FROM AUTHOR]

The aim of the study was to characterize strains of Listeria monocytogenes isolated from ready to eat (RTE) products collected as part of official food control and monitoring in Poland. A total of 105 L. monocytogenes isolates from RTE products: 54- cakes and 51 – delicatessen products were examined. The presence L. monocytogenes in cakes and delicatessen products was 0.4% and 0.7% respectively suggesting the level of contamination of RTE products with L. monocytogenes is very low. [ABSTRACT FROM AUTHOR]