Department of Veterinary Disease Biology, Faculty of Life Sciences, University of Copenhagen, Frederiksberg C, Denmark.
Vet Microbiol. 2010 May 19;142(3-4):379-86. doi: 10.1016/j.vetmic.2009.10.024. Epub 2009 Nov 6.
This study was performed to determine the origin and transmission of beta-lactam- and (fluoro)quinolone-resistant Escherichia coli in healthy, untreated broiler flocks. We focused on the dynamics of bacteria resistant to critically important antimicrobials for public and veterinary health in view of the possible link between antimicrobial resistant bacteria in farm animals and humans. By processing faecal samples collected with the sock method in broiler parent and broiler flocks, E. coli resistant to ampicillin and nalidixic acid were frequently isolated, while resistance to ciprofloxacin was detected at a very low frequency, and resistance to cephalosporins was not detected. Similarly, resistance to ampicillin and nalidixic acid were the only phenotypes detected in a collection of clinical E. coli isolates associated with first-week-mortality in broiler parent chicks. Although antimicrobial resistant E. coli were genetically diverse by means of amplified fragment length polymorphism (AFLP) typing, indistinguishable isolates were present in different flocks, including isolates from broiler parent chicks, broiler parents and broilers. In the absence of apparent selective pressure, the genotypic heterogeneity that we describe is likely the consequence of multiple introductions of antimicrobial resistant bacteria into the production system. The confinement under which broilers are raised limits the possibilities of bacterial transmission among different flocks. Our findings are consistent with vertical transmission of ampicillin- and nalidixic acid-resistant E. coli through the broiler production system. The persistence of antimicrobial resistant E. coli in healthy, untreated chicken flocks emphasises the need of careful evaluation of therapeutic options at any level of the broiler production.
本研究旨在确定健康未处理肉鸡群中β-内酰胺类和（氟喹诺酮类）耐药大肠杆菌的来源和传播。鉴于农场动物和人类之间可能存在抗生素耐药细菌的联系，我们关注对公共卫生和兽医健康至关重要的抗生素耐药细菌的动态。通过处理使用袜子法采集的肉鸡父母代和肉鸡群的粪便样本，经常分离出对氨苄西林和萘啶酸耐药的大肠杆菌，而对环丙沙星的耐药性检测频率非常低，并且未检测到对头孢菌素的耐药性。同样，在与肉鸡父母代雏鸡第一周死亡率相关的临床大肠杆菌分离株集合中，仅检测到对氨苄西林和萘啶酸的耐药表型。尽管通过扩增片段长度多态性（AFLP）分型发现抗生素耐药大肠杆菌具有遗传多样性，但在不同的鸡群中存在相同的分离株，包括来自肉鸡父母代雏鸡、肉鸡父母和肉鸡的分离株。在没有明显选择压力的情况下，我们描述的基因型异质性可能是抗生素耐药细菌多次引入生产系统的结果。肉鸡饲养的限制限制了不同鸡群之间细菌传播的可能性。我们的研究结果与通过肉鸡生产系统垂直传播氨苄西林和萘啶酸耐药大肠杆菌的结果一致。健康未处理的鸡群中抗生素耐药大肠杆菌的持续存在强调了在肉鸡生产的任何环节都需要仔细评估治疗选择的必要性。
