No abstract

No 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

Streptococcus anginosus together with S. constellatus and S. intermedius constitute the Streptococcus anginosus group (SAG), until recently considered to be benign commensals of the human mucosa isolated predominantly from oral cavity, but also from upper respiratory, intestinal, and urogenital tracts. For years the virulence potential of SAG was underestimated, mainly due to complications in correct species identification and their assignment to the physiological microbiota. Still, SAG representatives have been associated with purulent infections at oral and non-oral sites resulting in abscesses formation and empyema. Also, life threatening blood infections caused by SAG have been reported. However, the understanding of SAG as potential pathogen is only fragmentary, albeit certain aspects of SAG infection seem sufficiently well described to deserve a systematic overview. In this review we summarize the current state of knowledge of the S. anginosus pathogenicity factors and their mechanisms of action.

No abstract

Biofilms have a significant impact on food safety in the food industry. Many foodborne outbreaks have been associated with pathogenic strains that can form a biofilm. The present study aimed to examine the ability to form biofilms by pathogenic strains collected from retail food samples under the Official Control and Monitoring Program in Poland. Biofilm formation was assessed by the qualitative detection of EPS production on Congo Red Agar, tube method, crystal violet biofilm assay, and MTT assay. A total of 40 isolates from food samples (10 strains for each of the species Listeria monocytogenes, Staphylococcus aureus, Escherichia coli, and Bacillus cereus ) were examined. . . The study classifies strains as adherent strain, slightly adherent, nonadherent (A, SA and N); as weak, moderate, and strong biofilm formation (WBF, MBF and SBF); and weak, moderate, and high metabolic activity (WMA, MMA and HMA). Incubation conditions and time influenced the biofilm levels formed. Moreover, growth medium had a significant impact on biofilm formation. Results showed that 22.5% strains demonstrated A type in LBB and 77.5% SA type in LBB in the test tube while the stronger adhesion was obtained in BHI with 2% sucrose. Among the isolates incubated in the BHI medium with 2% sucrose, A type was observed in 60% of isolates (60%).. CV assay result show that the after 24 h incubation in LBB, SBP was 7,5% while after 48 h – 37.5% tested strains. For BHI medium supplemented with 2% sucrose after 24 h incubation strains 42.5% was classified as SBP and 37.6% after 48h.MTT assay result indicate that 15% strains incubate in LBB (24h) was HMA, and after 48h incubation time HMA show 25%. For BHI medium supplemented with 2% sucrose after 24 h or 48 h incubation strains 70% and 85 % was classified as HMA.

Silent genes are DNA sequences that are generally not expressed or expressed at a very low level. These genes become active as a result of mutation, recombination, or insertion. Silent genes can also be activated in laboratory conditions using pleiotropic, targeted genome-wide, or biosynthetic gene cluster approaches. Like every other gene, silent genes can spread through horizontal gene transfer. Most studies have focused on strains with phenotypic resistance, which is the most common subject. However, to fully understand the mechanism behind the spreading of antibiotic resistance, it is reasonable to study the whole resistome, including silent genes.

No abstract