Whole-genome sequencing of Streptococcus uberis isolated from cows with mastitis in Thuringia

<b>Introduction.</b> <i>Streptococcus uberis</i> is a common cause of mastitis in cattle, leading to significant economic losses. The widespread use of antimicrobials has contributed to the emergence of resistance, which poses a severe challenge in controlling <i>S. uberis</i> infection.<b>Aim.</b> The objective of this study was to gain insights into the antimicrobial resistance (AMR) and epidemiological typing of <i>S. uberis</i> isolated from milk collected from bovine mastitis on dairy farms in Thuringia.<b>Methodology.</b> In this study, 84 <i>S. uberis</i> isolates were obtained from cattle with clinical mastitis in Thuringia, their phenotypic and genotypic AMR were analyzed and their phylogenetic relationship was explored using whole-genome sequencing.<b>Results.</b> Genetically heterogeneous strains were found on the farms, but clusters of highly similar strains also circulated within the same farms. All isolates were sensitive to ampicillin, penicillin, ceftiofur, and vancomycin. However, 42.9%, 42.9%, 22.6%, 19.0%, and 13.0% were resistant to tetracycline, doxycycline, clindamycin, pirlimycin, and erythromycin, respectively. Thirty-nine strains were phenotypically resistant to two or more tested antibiotics. We identified a plasmid associated with macrolide and lincosamide resistance in 12% of the strains.<b>Conclusion.</b> The emergence of <i>S. uberis</i> strains resistant to multiple antibiotics highlights the importance of <i>S. uberis</i> surveillance and the prudent use of antimicrobials.