The use of the HRM method for identifying possible mutations in the ymoA gene region and evaluating their influence on the enterotoxic properties of Y. enterocolitica strains.

BACKGROUND: The yst gene that encodes the production of Yst enterotoxins is one of the most important and reliable virulence markers. Its ability to produce Yst has been demonstrated in pathogenic strains isolated from clinical cases of yersiniosis with diarrhea. However, not all yst positive strains produce enterotoxins. According to some authors, Yst production can be restored in a silent strain by ymoA mutation. In this study, the HRM method was applied to identify ymoA single nucleotide polymorphism with the aim of evaluating their influence on the enterotoxic properties of Y. enterocolitica strains. RESULTS: Two genotypes (A and G) of the examined nucleotide sequence and some variations were detected in the HRM analysis. A phylogenetic analysis of 10 genotype A nucleotide sequences revealed 100% similarity with the Yersinia enterocolitica subsp. enterocolitica 8081 genome NCBI Acc. No. AM286415. An analysis of 10 genotype G nucleotide sequences and 3 variations sequences revealed two point mutations in the examined region: transition A3387326G and insertion A in position 3387368. However, no mutations were observed in the coding region of any of the examined ymoA gene fragments. Genotype G was identified in nearly all Y. enterocolitica strains isolated from pigs. Only 4 nucleotide sequences were similar to AM286415 and did not feature point mutations. In case of human Y. enterocolitica strains 31 were classified as belonging to genotype A, the remaining 59 belonged to genotype G and were characterized by the presence of point mutations. CONCLUSIONS: No correlations were observed between enterotoxic properties and the presence of mutations in the ymoA gene region of Y. enterocolitica strains isolated from both humans and pigs.

Bioserotypes and virulence markers of Yersinia enterocolitica strains isolated from mallards (Anas platyrhynchos) and Pheasants (Phasianus colchicus).

Yersinia enterocolitica is the causative agent of yersiniosis in different animal species and in humans. Food contaminated with Y. enterocolitica is the main source of infection for humans, and swine plays a major role in the transmission of the disease. There are a limited number of reports of the prevalence of Y. enterocolitica in wild animals and birds. This study characterized virulence markers associated with Y. enterocolitica isolates recovered from mallards and pheasants. Y. enterocolitica strains were isolated from 5 (11.11%) of 45 mallards originating from a cold culture (peptone, sorbitol, and bile salts medium) belonging to biotype 1A. Serotyping showed that three of these five serotypes represented serotype O:8, one belonged to serotype O:5, and one did not agglutinate with any of the sera and was classified as nonidentified. Molecular analysis for virulence markers detected the ystB gene, which encodes an enterotoxin, in five isolates. Y. enterocolitica was not detected in any of the 16 examined pheasants.