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INTRODUCTION: Three Yersinia species were identified from samples of drinking water from diverse geographic regions of Ireland. Conventional commercial biochemical identification systems classified them as Yersinia enterocolitica. Since this organism is the most common cause of bacterial gastroenteritis in some countries, further investigation was warranted. The aim of the study was to provide a microbial characterisation of three Yersinia species, to determine their pathogenicity, and to review the incidence rate of Yersinia enterocolitica detection in our region. METHODS: Organism identification was performed using conventional commercial diagnostic systems MALDI-TOF, API 20E, API 50CHE, TREK Sensititre GNID and Vitek 2 GN, and whole genome sequencing (WGS) was performed. Historical data for detections was extracted from the lab system for 2008 to 2023. RESULTS: All three isolates gave "good" identifications of Yersinia enterocolitica on conventional systems. Further analysis by WGS matched two of the isolates with recently described Yersinia proxima, and the third was a member of the non-pathogenic Yersinia enterocolitica clade 1Aa. DISCUSSION: Our analysis of these three isolates deemed them to be Yersinia species not known currently to be pathogenic, but determining this necessitated the use of next-generation sequencing and advanced bioinformatics. Our work highlights the importance of having this technology available to public laboratories, either locally or in a national reference laboratory. The introduction of molecular technologies for the detection of Yersinia species may increase the rate of detections. Accurate identification of significant pathogens in environmental, public health and clinical microbiology laboratories is critically important for the protection of society.
ABSTRACT
Objective:To investigate the distribution and molecular characteristics of Yersinia isolated from diarrhea patients in Jiangsu Province. Methods:From 2017 to 2021, the stool samples of diarrhea patients were collected in Tongshan District of Xuzhou City and Dongtai City of Yancheng City, Jiangsu Province, where the national active monitoring sites of Yersinia enterocolitica, then Yersinia was isolated; meanwhile, suspected Yersinia strains were collected from sentinel hospitals in the province. The DNA of isolated strains was extracted for whole genome resequencing, and the data were uploaded to the EnteroBase database for Yersinia species identification; the original data were cleaned and processed for 16S ribosomal RNA (16S rRNA) gene polymorphism analysis. Five virulence genes (ail, ystA, ystB, yadA, virF) were scanned through the National Center for Biotechnology Information (NCBI) and Pathogen Virulence Factor Database (VFDB), and K-mer Tree was constructed and genomic characteristics were analyzed. Results:From 2017 to 2021, a total of 2 058 stool samples from diarrhea patients were collected, and 57 strains of Yersinia were isolated and identified; meanwhile, two Yersinia strains were collected from the sentinel hospital. Compared with EnteroBase database, 51 strains were identified as Yersinia enterocolitica, 4 strains as Yersinia proxima, 1 strain each as Yersinia aleksiciae, Yersinia massiliensis, Yersinia intermedia and Yersinia canariae. The 16S rRNA gene polymorphism analysis showed that all strains were clustered into 3 groups, which could distinguish Yersinia enterocolitica from other Yersinia. Among the 51 strains of Yersinia enterocolitica, 49 strains were virulence genotype Ⅲ(ail-, ystA-, ystB+, yadA-, virF-), two strains were virulence genotype Ⅱ(ail+, ystA+, ystB-, yadA-, virF-); and 8 other Yersinia strains were virulence genotype Ⅳ (ail-, ystA-, ystB-, yadA-, virF-). K-mer analysis could distinguish Yersinia enterocolitica from other Yersinia, JS-XZ-2020001 strain was far away from other Yersinia enterocolitica isolates, and serotype O8 strains were more concentrated. Conclusions:The clinical isolates of Yersinia enterocolitica from diarrhea patients are mainly Yersinia and other Yersinia co-exist in a small amount in Jiangsu Province, two new Yersinia species ( Yersinia proxima and Yersinia canariae) are discovered. The virulence genotype of Yersinia enterocolitica is mainly type Ⅲ. The 16S rRNA gene polymorphism analysis and K-mer analysis can effectively distinguish Yersinia enterocolitica from other Yersinia.
