Laboratory of Veterinary Pharmacokinetics and Pharmacodynamics, College of Veterinary Medicine, Kyungpook National University, Bukgu, Daegu, 41566, South Korea.
BMC Vet Res. 2020 Jan 28;16(1):22. doi: 10.1186/s12917-020-2246-5.
Antibiotics exposure has been implicated in the emergence of bacterial strains that are resistant to structurally related or unrelated antibiotics. Tylosin is a macrolide antibiotic that has been administered to treat respiratory pathogenic bacteria in swine. Thus, this study was undertaken to evaluate the impact of exposure to a constant (3 μg/mL) and decreasing concentrations of tylosin on the susceptibility of Salmonella enterica serovar Typhimurium to various antibiotics.
S. Typhimurium strains exposed to tylosin for 12 and 24 h in the in vitro dynamic model demonstrated at least an eight-fold increase in the minimum inhibitory concentrations (MICs) of florfenicol and tetracycline. Exposure to tylosin extended the lag-time of the growth curve and enhanced the generation of reactive oxygen species. Gene expression analysis demonstrated up-regulation of the acrAB and tolC Salmonella efflux pump genes and its global regulators (marA and soxS). Besides, the expression of ompC gene was down-regulated in tylosin exposed S. Typhimurium.
Exposure to decreasing concentrations of tylosin could reduce the susceptibility of S. Typhimurium to florfenicol and tetracycline.
抗生素暴露与结构相关或不相关的抗生素耐药细菌株的出现有关。泰乐菌素是一种大环内酯类抗生素，已被用于治疗猪的呼吸道病原菌。因此，本研究旨在评估暴露于恒定（3μg/mL）和降低浓度的泰乐菌素对肠炎沙门氏菌血清型鼠伤寒对各种抗生素敏感性的影响。
在体外动态模型中，暴露于泰乐菌素 12 和 24 小时的鼠伤寒沙门氏菌菌株对氟苯尼考和四环素的最小抑菌浓度（MIC）至少增加了 8 倍。暴露于泰乐菌素延长了生长曲线的延迟期，并增强了活性氧的产生。基因表达分析表明，acrAB 和 tolC 沙门氏菌外排泵基因及其全局调节剂（marA 和 soxS）上调。此外，暴露于泰乐菌素的鼠伤寒沙门氏菌中ompC 基因的表达下调。
暴露于降低浓度的泰乐菌素可降低鼠伤寒沙门氏菌对氟苯尼考和四环素的敏感性。
