Abstract：
Fluoroquinolones (FQ) are commonly used in dogs with bacterial skin infections. Their use as first choice, along with the increased incidence of FQ-resistance, represents a risk to animal and public health. Our study determined minimum inhibitory (MIC) and bactericidal (MBC) concentrations of five FQs in Staphylococcus aureus, Staphylococcus pseudintermedius, and Escherichia coli, together with FQ-resistance mechanisms. MICs, efflux pump (EP) overexpression and MBCs were measured in 249 skin infection isolates following CLSI guidelines (CLSI VET01-A4, CLSI M26-A). Chromosomal and plasmid-mediated resistance genes were investigated after DNA extraction and sequencing. FQ-resistance was detected in 10% of methicillin-susceptible (MS), 90% of methicillin-resistant (MR) staphylococci and in 36% of E. coli. Bactericidal effect was observed except in 50% of MRSA/P for ciprofloxacin and in 20% of MRSPs for enrofloxacin. Highest MICs were associated with double mutation in gyrA (Ser83Leu + Asp87Asn), efflux pumps and three PMQR genes in E. coli, and grlA (Ser80Phe + Glu84Lys) in S. aureus. EP overexpression was high among E. coli (96%), low in S. aureus (1%) and absent in S. pseudintermedius. Pradofloxacin and moxifloxacin showed low MICs with bactericidal effect. Since in vitro FQ resistance was associated with MR, FQ use should be prudently guided by susceptibility testing.
摘要：
氟喹诺酮类药物（FQ）通常用于患有细菌性皮肤感染的狗。它们作为第一选择，随着FQ抗性发生率的增加，对动物和公众健康构成风险。我们的研究确定了金黄色葡萄球菌中五种FQs的最低抑菌（MIC）和杀菌（MBC）浓度，假中间葡萄球菌,和大肠杆菌，以及FQ抗性机制。中等收入国家,根据CLSI指南（CLSIVET01-A4，CLSIM26-A），在249例皮肤感染分离株中测量了外排泵（EP）过表达和MBC。在DNA提取和测序后，研究了染色体和质粒介导的抗性基因。在10％的甲氧西林敏感（MS）中检测到FQ耐药性，90%的耐甲氧西林(MR)葡萄球菌和36%的大肠杆菌。除了环丙沙星在50％的MRSA/P和恩诺沙星在20％的MRSP中观察到杀菌效果。最高的MIC与gyrA（Ser83LeuAsp87Asn）的双重突变有关，大肠杆菌中的外排泵和三个PMQR基因，和grlA(Ser80Phe+Glu84Lys)在金黄色葡萄球菌中。EP过表达在大肠杆菌中很高（96%），金黄色葡萄球菌（1%）低，假中介葡萄球菌不存在。普拉多氟沙星和莫西沙星显示出低MIC，具有杀菌作用。由于体外FQ抗性与MR相关，药敏试验应谨慎指导FQ的使用。
