Determination of Minimum Inhibitory Concentrations of Selected Antibiotics Against Trueperella pyogenes Originated from Bovine Clinical Endometritis

Bacteriological examination of uterine secretions provides essential information for the prevalence of bovine uterine pathogens and their influence on fertility. The objective of the present study was to determine the uterine pathogens in cases of clinical endometritis in two Holstein-Friesian dairy farms between 21 and 27 days after calving and the minimum inhibitory concentration (MIC) of 14 antimicrobials for <i>Trueperella pyogenes</i> (<i>T. pyogenes</i>). Overall, the prevalence of <i>T. pyogenes</i> (Farms A and B) was 46.3% and 22% (<i>p</i> < 0.01), respectively. In contrast, Farm B had significantly more cases (<i>p</i> < 0.001) of <i>Escherichia coli</i>, but the distribution of uterine pathogens was similar. Regarding the prevalence of any bacteria, Farm B also had significantly more bacteria (<i>p</i> < 0.001) than Farm A. <i>T. pyogenes</i> isolates were highly susceptible to amoxicillin, amoxicillin/clavulanic acid, tylosin, and cephalosporins, such as ceftiofur, cefquinome, and cephalexin with MIC₉₀ of ≤2 μg/mL. At the same time, MIC₉₀ of tulathromycin, lincomycin, and florfenicol were between 4 and 8 μg/mL and of doxycycline, enrofloxacin, oxytetracycline, and gentamicin, were between 16 and 32 μg/mL, respectively. Meanwhile, sulfamethoxazole/trimethoprim showed the highest MIC₉₀ (>32 μg/mL). In summary, <i>T. pyogenes</i> with high MIC₉₀ against oxytetracycline, gentamicin, and sulfamethoxazole/trimethoprim were found, which calls attention to the prudent use of antibiotics.