College of Veterinary Medicine, Kyungpook National University, Daegu 41566, Republic of Korea.
Poult Sci. 2019 Mar 1;98(3):1480-1487. doi: 10.3382/ps/pey545.
This study was conducted to investigate the presence of plasmid-mediated quinolone resistance (PMQR) genes in β-lactamase-producing Escherichia coli isolates from layer hens and to characterize their molecular background. Among 142 E. coli isolates, 86 (60.6%) showed multidrug resistance and 15 (10.6%) were found to be β-lactamase-producing E. coli. Extended-spectrum β-lactamase (ESBL) and plasmid-mediated AmpC (pAmpC) β-lactamase genes, blaCTX-M-14 and blaCMY-2, were identified in three and six E. coli isolates, respectively. The non-ESBL or pAmpC gene, blaTEM-1, was found in eight of the isolates. Two isolates had both genes, blaCTX-M-14 and blaTEM-1. Among the 15 β-lactamase-producing E. coli, six PMQR genes, qnrS1 (n = 3) and qnrB4 (n = 3), were identified. Among the six PMQR-positive E. coli isolates, four exhibited double amino acid exchanges at both gyrA and parC with ciprofloxacin and enrofloxacin minimum inhibitory concentrations of ≥32 and ≥16 μg/mL, respectively. Additionally, five transconjugants (33.3%) showed a transferability of β-lactamase and PMQR genes. Pulsed-field gel electrophoresis (PFGE) analysis was conducted to investigate the 15 β-lactamase-producing E. coli isolates. In PFGE, E. coli included three PFGE patterns showing the same farms and in accordance with both β-lactamase and PMQR genes and the antimicrobial resistance pattern. Layer hens may act as a reservoir of antibiotic-resistant bacteria, and the PMQR gene in β-lactamase-producing E. coli isolates from layer hens has the potential to enter the food chain. Therefore, our findings suggest that comprehensive surveillance of antimicrobial use in laying operation systems is necessary.
本研究旨在调查来自蛋鸡的产β-内酰胺酶大肠杆菌分离株中存在的质粒介导的喹诺酮耐药（PMQR）基因，并对其分子背景进行特征分析。在 142 株大肠杆菌分离株中，86 株（60.6%）表现出多药耐药性，15 株（10.6%）被鉴定为产β-内酰胺酶大肠杆菌。在 3 株大肠杆菌分离株中发现了三种扩展谱β-内酰胺酶（ESBL）和质粒介导的 AmpC（pAmpC）β-内酰胺酶基因blaCTX-M-14和blaCMY-2，在 6 株大肠杆菌分离株中发现了非 ESBL 或 pAmpC 基因 blaTEM-1。8 株分离株中发现了 blaTEM-1 基因。在 15 株产β-内酰胺酶大肠杆菌中，鉴定出 6 种 PMQR 基因，qnrS1（n=3）和 qnrB4（n=3）。在 6 株 PMQR 阳性大肠杆菌分离株中，有 4 株对环丙沙星和恩诺沙星的最小抑菌浓度分别≥32 和≥16μg/ml 时，gyrA 和 parC 都出现了两种氨基酸的交换。此外，5 株转导体（33.3%）表现出对β-内酰胺酶和 PMQR 基因的可转移性。进行脉冲场凝胶电泳（PFGE）分析以研究 15 株产β-内酰胺酶大肠杆菌。在 PFGE 中，大肠杆菌包括三种 PFGE 模式，这些模式显示来自相同的农场，与β-内酰胺酶和 PMQR 基因以及抗菌药物耐药模式一致。蛋鸡可能是抗生素耐药菌的储存库，产β-内酰胺酶大肠杆菌分离株中的 PMQR 基因有可能进入食物链。因此，我们的研究结果表明，有必要对蛋鸡养殖系统中抗生素使用进行全面监测。
