Isolation, characterization and antimicrobial resistance of Yersinia enterocolitica from Polish cattle and their carcasses.

BACKGROUND: Yersinia enterocolitica is a heterogeneous bacterial species that has been divided into six biotypes and more than 70 serotypes. Each year, the European Food Safety Authority classifies yersiniosis caused by Y. enterocolitica as one of the most important zoonotic diseases. The prevalence of Y. enterocolitica in cattle has not been thoroughly analyzed in Poland, and beef and bovine carcasses contaminated with antimicrobial resistant Y. enterocolitica pose a health risk for both, farm workers and consumers. Therefore, the aim of this study was to evaluate the prevalence of Y. enterocolitica in cattle and to determine the antimicrobial susceptibility of the isolated strains. RESULTS: A total of 1020 samples were analyzed, including 660 rectal swabs collected from live cattle and 360 swabs from cold-stored beef carcasses. The results of this study indicate that Y. enterocolitica was isolated from three of the 15 examined cattle herds and the prevalence within these herds ranged from 0% to nearly 32%. Y. enterocolitica was isolated from 14.7% of the examined heifers, 7.4% of calves and 5.5% of adult cows. More than 65% of the strains were isolated from cold enrichment. The strains isolated from live cattle tested positive for the ystB gene, while ail and ystA genes were not found. Most of the isolated strains belonged to bioserotype 1A/NT. The majority of the isolated strains were resistant to ampicillin, cefalexin and amoxicillin with clavulanic acid, however these are expected phenotypes for Y. enterocolitica. CONCLUSIONS: The results of this study indicate that Y. enterocolitica is present in cattle herds in Poland. The strains isolated from live cattle were ystB-positive, most of them belonged to bioserotype 1A/NT. The prevalence of Y. enterocolitica strains was generally low in cold-stored beef carcasses.

The Role of Peroxisome Proliferator-Activated Receptors in PGF2α-Induced Luteolysis in the Bovine Corpus Luteum.

The participation of peroxisome proliferator-activated receptors (PPARs) in ovarian function in cattle is still not fully understood. The aim of this in vitro study was to determine: (i) the immunolocalization, mRNA expression and tissue concentration of PPARα, PPARδ and PPARγ in the bovine corpus luteum (CL) (n = 40) throughout the estrous cycle, and (ii) the involvement of PPAR in PGF2α-induced processes related to luteolysis. CL (n = 9) explants were cultured in the presence of PPAR antagonists (10-5 M) in combination with or without PGF2α receptor antagonist (10-5 M) and PGF2α (10-6 M). The mRNA and protein expression of PPARs was evaluated through qPCR, IHC, and ELISA, respectively. The results showed that PPAR mRNA and protein expression differed according to the luteal stages. PGF2α upregulated PPARδ and PPARγ mRNA expression in the bovine CL in vitro, whereas PPARγ increased the inhibitory effect of PGF2α by decreasing progesterone secretion and the mRNA expression of hydroxy-delta-5-steroid dehydrogenase, 3 ß- and steroid delta-isomerase 1 (HSD3B1) in the CL explants; mRNA transcription of tumor necrosis factor α (TNFα) and inducible nitric oxide synthase (iNOS) was increased. The obtained results indicate that the mRNA and protein expression of PPARs changes in the bovine CL throughout the estrous cycle and under the influence of PGF2α. We suggest that isoform γ, among all examined PPARs, could be a factor involved in the regulation of PGF2α-induced processes related to luteolysis in the bovine CL. Further studies are needed to understand the role of PPAR in luteal regression in the CL of cattle.

The Most Important Virulence Markers of Yersinia enterocolitica and Their Role during Infection.

Yersinia enterocolitica is the causative agent of yersiniosis, a zoonotic disease of growing epidemiological importance with significant consequences for public health. This pathogenic species has been intensively studied for many years. Six biotypes (1A, 1B, 2, 3, 4, 5) and more than 70 serotypes of Y. enterocolitica have been identified to date. The biotypes of Y. enterocolitica are divided according to their pathogenic properties: the non-pathogenic biotype 1A, weakly pathogenic biotypes 2⁻5, and the highly pathogenic biotype 1B. Due to the complex pathogenesis of yersiniosis, further research is needed to expand our knowledge of the molecular mechanisms involved in the infection process and the clinical course of the disease. Many factors, both plasmid and chromosomal, significantly influence these processes. The aim of this study was to present the most important virulence markers of Y. enterocolitica and their role during infection.