Department of Food Hygiene and Environmental Health, Faculty of Veterinary Medicine, P.O. Box 66, FI-00014 University of Helsinki, Finland.
Vet Microbiol. 2011 Jun 2;150(3-4):322-30. doi: 10.1016/j.vetmic.2011.02.008. Epub 2011 Feb 18.
Effects of danofloxacin or consecutive fluoroquinolone and macrolide treatments on resistance development in Campylobacter have remained uncharacterised. Therefore we analysed the development of resistance in porcine Campylobacter coli before and after danofloxacin and tylosin treatments at a farrowing farm. Danofloxacin-treated (n=12, group A) and control pigs (n=15, group B) were subsequently treated with tylosin and sampled longitudinally. C. coli were isolated and susceptibilities to ciprofloxacin and erythromycin were assessed, isolates were genotyped with PFGE and resistance-related mutations were identified. Isolates from the danofloxacin-treated pigs had more frequently non-wild type MICs (above the epidemiological cut-off value (ECOFF)) for ciprofloxacin (P<0.001) and erythromycin (P<0.05) than those isolated before danofloxacin or those from the controls. Subsequent tylosin treatment increased proportion of isolates with non-wild type MICs for erythromycin in both groups A and B (P<0.01) and, interestingly, proportion of isolates with non-wild type MICs for ciprofloxacin in group B (P<0.001) with high MICs (128 μg/ml). PFGE analysis revealed treatments selecting predominant genotypes with variable resistance patterns and decreasing initial diversity of genotypes. The most common genotype had mainly high MICs for ciprofloxacin among danofloxacin-treated pigs but wild type MICs (below the ECOFF) among the controls housed in the same pens. This suggests that the non-wild type isolate was rarely transmitted or outcompeting wild type genotype in the control pigs without selection pressure. Isolates exhibiting non-wild type MICs for ciprofloxacin harboured the C257T (Thr-86-Ile) mutation in the gyrA gene. In conclusion, a high dose of danofloxacin used at the farm did not prevent emergence of isolates with high MICs for ciprofloxacin. After subsequent tylosin treatment isolates had even higher MICs for ciprofloxacin and erythromycin than before the treatment. Therefore, controlled use of antimicrobials in food animal production is essential.
氟甲喹或连续氟喹诺酮和大环内酯类药物治疗对弯曲杆菌耐药性的影响尚未确定。因此，我们分析了在分娩场用丹氟沙星和泰乐菌素治疗前后猪弯曲杆菌的耐药性发展情况。丹氟沙星治疗组（n=12，A 组）和对照组（n=15，B 组）猪随后接受泰乐菌素治疗，并进行纵向采样。分离出 C. coli 并评估其对环丙沙星和红霉素的敏感性，对分离株进行 PFGE 基因分型，并鉴定耐药相关突变。丹氟沙星治疗组猪的分离株对环丙沙星（P<0.001）和红霉素（P<0.05）的非野生型 MIC（高于流行病学临界点（ECOFF））的频率高于丹氟沙星治疗前或对照组的分离株。随后的泰乐菌素治疗增加了两组 A 和 B 中红霉素非野生型 MIC 分离株的比例（P<0.01），有趣的是，B 组中对环丙沙星非野生型 MIC（P<0.001）的分离株比例升高，MIC 值较高（128 μg/ml）。PFGE 分析显示，治疗选择了具有不同耐药模式的主要基因型，并降低了初始基因型的多样性。在丹氟沙星治疗的猪中最常见的基因型主要具有较高的环丙沙星 MIC，但在同一围栏中饲养的对照组中具有野生型 MIC（低于 ECOFF）。这表明在没有选择压力的情况下，非野生型分离株很少在对照组猪中传播或竞争野生型基因型。表现出环丙沙星非野生型 MIC 的分离株携带有 gyrA 基因的 C257T（Thr-86-Ile）突变。总之，在农场使用高剂量的丹氟沙星并不能防止出现环丙沙星 MIC 值较高的分离株。随后的泰乐菌素治疗后，分离株对环丙沙星和红霉素的 MIC 值甚至高于治疗前。因此，在食品动物生产中必须控制使用抗生素。
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