氟喹诺酮类耐药大肠杆菌的分子特征从仔猪大肠杆菌病分离。
Molecular characteristics of fluoroquinolone-resistant Escherichia coli isolated from suckling piglets with colibacillosis.
机构信息
Korea Zoonosis Research Institute, Jeonbuk National University, Iksan, 54531, Republic of Korea.
College of Veterinary Medicine, Chungbuk National University, Cheongju, 28644, Korea.
出版信息
BMC Microbiol. 2022 Sep 15;22(1):216. doi: 10.1186/s12866-022-02632-9.
OBJECTIVES
Colibacillosis is a frequent enteric disease in the pig industry that causes significant economic losses. The objective of this study was to investigate the molecular characteristics of fluoroquinolone (FQ)-resistant E. coli isolates from suckling piglets with colibacillosis.
RESULTS
A total of 43 FQ-resistant E. coli isolates were tested in this study and all isolates showed multi-drug resistance (MDR) and mutations in quinolone resistance determining regions (gyrA or parC). Especially, FQ-resistant E. coli isolates with double mutations in both gyrA and parC were shown a high FQs minimum inhibitory concentration (≥ 64 mg/L for ciprofloxacin, ≥ 128 mg/L for enrofloxacin, and ≥ 256 mg/L for norfloxacin). Among 43 FQ-resistant E. coli isolates, 12 (27.9%) were showed plasmid-mediated quinolone resistance (PMQR) positive E. coli. Prevalence of PMQR gene, aac(6')-Ib-cr, qnrS, and qepA, were identified in 7, 3, and 2 E. coli isolates, respectively. We identified the following in PMQR-positive E. coli isolates: the tetracycline resistance genes tetD (12 isolates, 100.0%), tetE (12 isolates, 100.0%), tetA (11 isolates, 91.7%), and tetB (1 isolate, 8.3%); β-lactamases-encoding blaCMY-2 (10 isolates, 83.3%), blaTEM-1 (7 isolates, 58.3%), blaOXA-1 (7 isolates, 58.3%), blaSHV-1 (3 isolates, 16.7%), and blaAAC-2 (1 isolate, 8.3%); and the chloramphenicol resistance genes (10 isolates, 83.3%); the sulfonamide resistance genes sul1 (9 isolates, 75.0%) and sul2 (10 isolates, 83.3%); the aminoglycoside modifying enzyme gene aac(3)-II (2 isolates, 16.7%). The F4 (7 isolates, 58.3%), LT:STb:EAST1 (5 isolates, 41.7%), and paa (3 isolates, 25.0%) were most common fimbrial antigen, combinations of toxin genes, and non-fimbrial adhesins genes, respectively. All PMQR-positive E. coli carried class I integrons but only 4 isolates carried the gene cassette. The most prevalent plasmid replicon was FIB (9 isolates, 75.0%), followed by FIC, HI1, and N (7 isolates, 58.3%), respectively.
CONCLUSIONS
Because FQ-resistant E. coli can serve as a reservoir of FQ resistant genetic determinants that can be transferred to pathogenic bacteria in humans or pigs, this represents a public health hazard.
目的
大肠杆菌病是猪养殖业中一种常见的肠道疾病，会造成重大经济损失。本研究旨在调查具有大肠杆菌病的仔猪中氟喹诺酮（FQ）耐药分离株的分子特征。
结果
本研究共检测了 43 株 FQ 耐药大肠杆菌分离株，所有分离株均表现出多重耐药性（MDR）和喹诺酮耐药决定区（gyrA 或 parC）的突变。特别是，在 gyrA 和 parC 均发生双重突变的 FQ 耐药大肠杆菌分离株中，氟喹诺酮的最低抑菌浓度（MICS）较高（环丙沙星≥64mg/L，恩诺沙星≥128mg/L，诺氟沙星≥256mg/L）。在 43 株 FQ 耐药大肠杆菌分离株中，有 12 株（27.9%）表现为质粒介导的氟喹诺酮耐药（PMQR）阳性大肠杆菌。我们在 7 株、3 株和 2 株大肠杆菌分离株中分别鉴定出了 PMQR 基因 aac(6')-Ib-cr、qnrS 和 qepA。在 PMQR 阳性大肠杆菌分离株中还鉴定出了以下基因：四环素耐药基因 tetD（12 株，100.0%）、tetE（12 株，100.0%）、tetA（11 株，91.7%）和 tetB（1 株，8.3%）；β-内酰胺酶编码基因 blaCMY-2（10 株，83.3%）、blaTEM-1（7 株，58.3%）、blaOXA-1（7 株，58.3%）、blaSHV-1（3 株，16.7%）和 blaAAC-2（1 株，8.3%）；氯霉素耐药基因（10 株，83.3%）；磺胺类耐药基因 sul1（9 株，75.0%）和 sul2（10 株，83.3%）；氨基糖苷类修饰酶基因 aac(3)-II（2 株，16.7%）。F4（7 株，58.3%）、LT:STb:EAST1（5 株，41.7%）和 paa（3 株，25.0%）是最常见的菌毛抗原、毒素基因组合和非菌毛黏附素基因。所有 PMQR 阳性大肠杆菌均携带 I 类整合子，但只有 4 株携带基因盒。最常见的质粒复制子是 FIB（9 株，75.0%），其次是 FIC、HI1 和 N（7 株，58.3%）。
结论
由于 FQ 耐药大肠杆菌可作为 FQ 耐药遗传决定因子的储存库，这些因子可转移到人类或猪中的致病性细菌中，因此这代表了一种公共卫生危害。
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