Prudent Antimicrobial Use Is Essential to Prevent the Emergence of Antimicrobial Resistance in Yersinia enterocolitica 4/O:3 Strains in Pigs

Yersinia enterocolitica biovar 1A: An underappreciated potential pathogen in the food chain

Yersinia enterocolitica is an underreported cause of foodborne gastroenteritis. Little is known of the diversity of Y. enterocolitica isolated from food and which food commodities contribute to human disease. In this study, Y. enterocolitica was isolated from 37/50 raw chicken, 8/10 pork, 8/10 salmon and 1/10 leafy green samples collected at retail in the UK. Up to 10 presumptive Y. enterocolitica isolates per positive sample underwent whole genome sequencing (WGS) and were compared with publicly available genomes. In total, 207 Y. enterocolitica isolates were analyzed and belonged to 38 sequence types (STs). Up to five STs of Y. enterocolitica were isolated from individual food samples and isolates belonging to the same sample and ST differed by 0-74 single nucleotide polymorphisms (SNPs). Biotype was predicted for 205 (99 %) genomes that all belonged to biotype 1A, previously described as non-pathogenic. However, around half (51 %) of food samples contained isolates belonging to the same ST as previously isolated from UK human cases. The closest human-derived isolates shared between 17 and 7978 single nucleotide polymorphisms (SNPs) with the food isolates. Extensive food surveillance is required to determine what food sources are responsible for Y. enterocolitica infections and to re-examine the role of biotype 1A as a human pathogen.

Enteropathogenic Yersinia with Public Health Relevance Found in Dogs and Cats in Finland

Yersiniosis is a common zoonotic enteric disease among humans, which has been linked to pigs and contaminated food, especially pork. The epidemiology of yersiniosis is still obscure, and studies on yersiniosis in pets are very scarce. In this study, we performed pheno- and genotypic characterisation of 50 Yersinia strains isolated from pets in Finland between 2012 and 2023. Y. enterocolitica 4/O:3/ST135, the most common type in human yersiniosis, was also the most common type (68%) found in clinical faecal samples in our study. Also, human pathogenic Y. enterocolitica 2/O:9/ST139 and Y. pseudotuberculosis O:1/ST9 and O:1/ST42 strains carrying all essential pathogenic genes were identified. Three Y. enterocolitica 4/O:3/ST9 strains were multi-drug-resistant and two of them were highly related, showing one allelic difference (AD) with core genome multi-locus sequence typing. Non-pathogenic, genotypically highly diverse Y. enterocolitica 1A strains, showing more than 1000 ADs and missing the essential virulence genes, were also recognised in dogs and cats. Our study demonstrates that pets can excrete human pathogenic Yersinia in their faeces and may serve as an infection source for human yersiniosis, especially in families with small children in close contact with their pets.

Higher Resistance of Yersinia enterocolitica in Comparison to Yersinia pseudotuberculosis to Antibiotics and Cinnamon, Oregano and Thyme Essential Oils

Yersiniosis is an important zoonotic disease; however, data are scarce on the resistance of enteropathogenic yersiniae, especially that of Y. pseudotuberculosis. Minimum inhibitory concentrations (MIC) of 21 antibiotics and 3 essential oils (EOs) were determined by broth microdilution for Y. enterocolitica bioserotype 4/O:3 strains isolated from domestic swine (n = 132) and Y. pseudotuberculosis strains isolated from wild boars (n = 46). For 15 of 21 antibiotics, statistically significant differences were found between MIC values of Y. enterocolitica and Y. pseudotuberculosis. While Y. enterocolitica was more resistant to amoxiclav, ampicillin, cefotaxime, cefuroxime, gentamicin, imipenem, meropenem, tetracycline, tobramycin, and trimethoprim, Y. pseudotuberculosis was more resistant to cefepime, ceftazidime, colistin, erythromycin, and nitrofurantoin. Statistically significant differences were found between various essential oils (p < 0.001) and species (p < 0.001). The lowest MICs for multiresistant Y. enterocolitica (n = 12) and Y. pseudotuberculosis (n = 12) were obtained for cinnamon (median 414 and 207 μg/mL, respectively) and oregano EOs (median 379 and 284 μg/mL), whereas thyme EO showed significantly higher MIC values (median 738 and 553 μg/mL; p < 0.001). There was no difference between Y. enterocolitica strains of plant (1A) and animal (4/O:3) origin (p = 0.855). The results show that Y. enterocolitica is generally more resistant to antimicrobials than Y. pseudotuberculosis.