The world's first isolation of multidrug-resistant Yersinia enterocolitica strains from Shetland ponies

Y. enterocolitica and Y. pseudotuberculosis are the causative agents of yersiniosis - zoonosis important for public health. The aim of this study was to detect the presence of Y. enterocolitica and Y. pseudotuberculosis in tundra reindeer, European mouflons and Shetland ponies, determine the bioserotype and genotype of the isolated strains, and assess their susceptibility to antimicrobial agents. To the authors' knowledge, this is the first study in world literature on the occurrence and characteristics of Y. enterocolitica strains in Shetland ponies. Five molecularly confirmed strains of Y. enterocolitica were isolated from 7 Shetland ponies (71.4%) and one from 9 European mouflons (11.1%). Y. enterocolitica was not isolated from tundra reindeer and Y. pseudotuberculosis was not isolated from any of the tested species. All Y. enterocolitica strains belonged to biotype 1 A and were ystB-positive. Strains isolated from Shetland ponies were classified as genotype G1, while strain isolated from a European mouflon was defined as genotype G3. Two of the strains isolated from Shetland ponies showed resistance to five antimicrobial agents, another two strains were resistant to six chemotherapeutic agents and the last two strains - one from Shetland pony and one from European mouflon, showed resistance to seven chemotherapeutic agents. All strains were susceptible only to ciprofloxacin. The results of this study showed that ystB-positive, multidrug resistant Y. enterocolitica strains are present in Shetland ponies and direct contact of children and adults with these animals may pose a potential threat.