Isolates from Livestock and European Bison () as a Reservoir of Tetracycline Resistance Determinants.

Determinants of tetracycline resistance in are still poorly known. In this study, resistance to tetracycline was investigated in 114 isolates from livestock and European bison. Tetracycline minimum inhibitory concentration (MIC) was evaluated by a microdilution method, and tetracycline resistance genes were detected by PCR. To determine variants of and their linkage with mobile elements, sequencing analysis was performed. Among the studied isolates, 43.0% were tetracycline resistant (MIC ≥ 8 µg/mL). The highest MIC of tetracycline (32 µg/mL) was noted in bovine and European bison isolates. The most prevalent determinant of tetracycline resistance was (in 40.4% of isolates), while was detected only in 8.8% of isolates. Four variants of (, , , ) were recognized. The variant was the most frequent and was linked to the ATE-1 transposon. The 2 variant, found in a swine isolate, was not previously reported in . This is the first report on determinants of tetracycline resistance in isolates from European bison. These findings highlight that wild animals, including wild ruminants not treated with antimicrobials, can be a reservoir of tetracycline-resistant bacteria carrying resistance determinants, which may be easily spread among pathogenic and environmental microorganisms.