Virulence Determinants and Genetic Diversity of Yersinia Species Isolated from Retail Meat.

Margarita Terentjeva,Olga Valciņa,Madara Streikiša,Silva Gradovska,Juris Ķibilds,Irēna Meistere,Jevgēnija Ošmjana,Laura Alksne

doi:10.3390/pathogens11010037

Abstract

Yersinia enterocolitica is an important foodborne pathogen, and the determination of its virulence factors and genetic diversity within the food chain could help understand the epidemiology of yersiniosis. The aim of the present study was to detect the prevalence, and characterize the virulence determinants and genetic diversity, of Yersinia species isolated from meat. A total of 330 samples of retailed beef (n = 150) and pork (n = 180) in Latvia were investigated with culture and molecular methods. Whole genome sequencing (WGS) was applied for the detection of virulence and genetic diversity. The antimicrobial resistance of pathogenic Y. enterocolitica isolates was detected in accordance with EUCAST. Yersinia species were isolated from 24% (79/330) of meats, and the prevalence of Y. enterocolitica in pork (24%, 44/180) was significantly higher (p < 0.05) than in beef (13%, 19/150). Y. enterocolitica pathogenic bioserovars 2/O:9 and 4/O:3 were isolated from pork samples (3%, 6/180). Only resistance to ampicillin was confirmed in Y. enterocolitica 4/O:3 and 2/O:9 isolates, but not in other antimicrobials. Major virulence determinants, including ail, inv, virF, ystA and myfA, were confirmed with WGS in Y. enterocolitica 2/O:9 and 4/O:3. MLST typing revealed 15 STs (sequence types) of Y. enterocolitica with ST12 and ST18, which were associated with pathogenic bioserovars. For Y. enterocolitica 1A, Y. kristensenii, Y. intermedia and Y. frederiksenii, novel STs were registered (ST680-688). The presence of virulence genes and genetic characteristics of certain Y. enterocolitica STs confirm the common knowledge that pork could be an important source of pathogenic Yersinia.

Highlights

The Yersinia genus currently consists of 28 species, of which three are human pathogenic, while others are considered as non-pathogenic, Yersinia-like microorganisms [1,2]
The highest number of Yersinia was found in pork cuts with five isolated species: Y. enterocolitica (23%, 36/160), Y. intermedia (3%, 4/160), Y. kristensenii (1%, 1/160) and Y. frederiksenii (2%, 1/160)
The lowest diversity of the Yersinia species was recovered from beef, where 19% (13/150) of Y. enterocolitica- and 4% (6/150) of Y. intermedia-positive samples were identified

Summary

Introduction

The Yersinia genus currently consists of 28 species, of which three are human pathogenic, while others are considered as non-pathogenic, Yersinia-like microorganisms [1,2]. Pathogenic Yersinia enterocolitica and Yersinia pseudotuberculosis are reported to cause yersiniosis, which is a zoonotic foodborne infection characterized by gastrointestinal manifestations, and postinfection sequelas, such as reactive arthritis or erythema nodosum [3,4]. Y. enterocolitica is a very heterogeneous species and is divided into six biotypes and various serogroups with different bioserovars showing distinctive virulence properties, hosts and geographical distribution [1]. Y. enterocolitica biotype 1A is non-pathogenic since it lacks classical virulence markers, which are important for the invasion of the human host and survival in the organisms [4,6,7]. Non-pathogenic Yersinia and Y. enterocolitica are widely distributed in the environment, animals and food and were isolated from clinical patients [8,9]. Y. enterocolitica biotypes 1B-5 are pathogenic, and bioserovars of 2/O:5,27, 2/O:9, 3/O:3 and 4/O:3 were recorded in clinical cases in Europe [1]

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