Kaspersen Håkon, Fiskebeck Eve Zeyl, Sekse Camilla, Slettemeås Jannice Schau, Urdahl Anne Margrete, Norström Madelaine, Lagesen Karin, Simm Roger
Norwegian Veterinary Institute, Oslo, Norway.
Institute of Oral Biology, University of Oslo, Oslo, Norway.
Front Microbiol. 2020 May 19;11:938. doi: 10.3389/fmicb.2020.00938. eCollection 2020.
Quinolones are important antimicrobials for both humans and animals, and resistance toward these compounds is a serious threat to public health. In Norway, quinolone resistant (QREC) have been detected at low levels in a high proportion of broiler flocks, even without the use of quinolones in rearing of broilers. Due to the pyramidal structure of broiler breeding, QREC isolates may be disseminated from grandparent animals down through the pyramid. However, quinolone resistance can also develop in wild type through specific chromosomal mutations, and by horizontal acquisition of plasmid-mediated quinolone resistance genes. The goal of this study was to determine whether QREC is disseminated through the broiler breeding pyramid or developed locally at some stage in the broiler production chain. For this purpose, we whole genome sequenced wild type- and QREC isolates from broiler and parent flocks that had been isolated in the Norwegian monitoring program for antimicrobial resistance in feed, food and animals (NORM-VET) between 2006 and 2017, from 22 different production sites. The sequencing data was used for typing of the isolates, phylogenetic analysis and identification of relevant resistance mechanisms. Highly similar QREC isolates were identified within major sequence types from multiple production sites, suggesting dissemination of QREC isolates in the broiler production chain. The occurrence of potential resistance development among the WT was low, indicating that this may be a rare phenomenon in the Norwegian broiler production. The results indicate that the majority of the observed QREC at the bottom of the broiler production pyramid originates from parent or grandparent animals. These results highlight the importance of surveillance at all levels of the broiler production pyramid and of implementation of proper biosecurity measures to control dissemination of QREC.
喹诺酮类药物对人类和动物来说都是重要的抗菌剂，而对这些化合物的耐药性是对公众健康的严重威胁。在挪威，即使在肉鸡饲养过程中未使用喹诺酮类药物，仍在高比例的肉鸡群中检测到低水平的喹诺酮耐药菌（QREC）。由于肉鸡育种的金字塔结构，QREC分离株可能会从祖代动物向下通过金字塔进行传播。然而，喹诺酮耐药性也可通过野生型细菌的特定染色体突变以及通过水平获得质粒介导的喹诺酮耐药基因而产生。本研究的目的是确定QREC是通过肉鸡育种金字塔传播，还是在肉鸡生产链的某个阶段在本地产生。为此，我们对2006年至2017年间在挪威饲料、食品和动物抗菌药物耐药性监测项目（NORM-VET）中从22个不同生产地点分离的肉鸡和种鸡群的野生型和QREC分离株进行了全基因组测序。测序数据用于分离株分型、系统发育分析以及相关耐药机制的鉴定。在来自多个生产地点的主要序列类型中鉴定出高度相似的QREC分离株，这表明QREC分离株在肉鸡生产链中发生了传播。野生型细菌中潜在耐药性产生的发生率较低，这表明在挪威肉鸡生产中这可能是一种罕见现象。结果表明，在肉鸡生产金字塔底部观察到的大多数QREC起源于种鸡或祖代动物。这些结果突出了对肉鸡生产金字塔各级进行监测以及实施适当生物安全措施以控制QREC传播的重要性。
