Yersinia enterocolitica, widespread within domestic and wild-living animals, is a foodborne pathogen causing yersiniosis. The goal of this study was to assess a genetic similarity of Y. enterocolitica and Y. enterocolitica-like strains isolated from different hosts using Multiple Locus Variable-Number Tandem Repeat Analysis (MLVA) and Pulsed-Field Gel Electrophoresis (PFGE) methods, and analyze the prevalence of virulence genes using multiplex-Polymerase Chain Reaction (PCR) assays. Among 51 Yersinia sp. strains 20 virulotypes were determined. The most common virulence genes were ymoA, ureC, inv, myfA, and yst. Yersinia sp. strains had genes which may contribute to the bacterial invasion and colonization of the intestines as well as survival in serum. One wild boar Y. enterocolitica 1A strain possessed ail gene implying the possible pathogenicity of 1A biotype. Wild boar strains, represented mainly by 1A biotype, were not classified into the predominant Variable-Number Tandem Repeats (VNTR)/PFGE profile and virulotype. There was a clustering tendency among VNTR/PFGE profiles of pig origin, 4/O:3, and virulence profile. Pig and human strains formed the most related group, characterized by ~80% of genetic similarity what suggest the role of pigs as a potential source of infection for the pork consumers.

Nanoparticles can interact with the complement system and modulate the inflammatory response. The effect of these interactions on the complement activity strongly depends on physicochemical properties of nanoparticles. The interactions of silver nanoparticles with serum proteins (particularly with the complement system components) have the potential to significantly affect the antibacterial activity of serum, with serious implications for human health. The aim of the study was to assess the influence of graphite oxide (GO) nanocomposites (GO, GO-PcZr(Lys)₂-Ag, GO-Ag, GO-PcZr(Lys)₂) on the antibacterial activity of normal human serum (NHS), serum activity against bacteria isolated from alveoli treated with nanocomposites, and nanocomposite sensitivity of bacteria exposed to serum in vitro (using normal human serum). Additionally, the in vivo cytotoxic effect of the GO compounds was determined with application of a Galleria mellonella larvae model. GO-PcZr(Lys)₂, without IR irradiation enhance the antimicrobial efficacy of the human serum. IR irradiation enhances bactericidal activity of serum in the case of the GO-PcZr(Lys)₂-Ag sample. Bacteria exposed to nanocomposites become more sensitive to the action of serum. Bacteria exposed to serum become more sensitive to the GO-Ag sample. None of the tested GO nanocomposites displayed a cytotoxicity towards larvae.

Red blood cell (RBC) concentrates remain at risk of bacterial contamination during cold storage. Although infrequent, Yersinia enterocolitica poses a significant blood safety risk. This study aimed to assess Y. enterocolitica bioserotype growth in RBC concentrates, serum sensitivity, and genetic diversity including iron metabolism genes. Ten Y. enterocolitica isolates from bioserotypes 1A, 1B/O:8, 4/O:3, and 2/O:9 were incubated in RBC concentrates and counted on days 3, 7, 14, 21, and 28. After incubation, the isolates were tested in human serum (NHS). Eight genomes were sequenced, analyzed using cgMLST, and screened for iron metabolism genes. The isolates formed two clusters, with 186dz (1A) and Ye8 (1B/O:8) as singletons. After 28 days in the RBC concentrates, the bacterial counts ranged from 1.98 × 10⁵ to 1.2 × 10⁹ CFU/mL, with Ye8 (1B/O:8) achieving the highest growth and one 4/O:3 isolate showing the lowest. All isolates survived 15–30 min in NHS, but the 28s isolate did not survive at 60 min. Serum sensitivity increased in two isolates, decreased in three, and remained unchanged in five. Isolates contained 27–42 iron metabolism genes with multiple allelic variants. The iron metabolism gene content or variants may influence the growth of Y. enterocolitica in RBC.