摘要

       本研究旨在表征从澳大利亚（1999-2005 年）的断奶后腹泻病例中收集的多重耐药性产肠毒素大肠杆菌 (ETEC) 分离株（n = 117）中的抗菌素耐药性和毒力基因。对分离株进行血清分型，对 12 种抗菌药物进行抗生素谱表型分析，并通过 PCR 对 30 种质粒介导的抗菌素耐药基因 (ARG)、22 种肠道和 38 种肠外大肠杆菌毒力基因 (VG) 进行基因分型。确定了九个血清群，最普遍的是 O149 (46.2%)、O141 (11.2%) 和 Ont (31.6%)。没有一个分离株对头孢噻呋或恩诺沙星有耐药性，9.4% 的分离株对氟苯尼考耐药。未检测到相应的超广谱/AmpC β-内酰胺酶、氟喹诺酮或floR ARG。抗菌素耐药性指数 (ARI) 是根据组合数据计算得出的，每种抗菌剂的权重取决于其对人类健康的重要性。由于氨基糖苷类 ARGs 的流行率升高和拥有更多毒力基因 (VGs)，包括 ExPEC 或 EHEC 粘附素（bmaE、sfa/focDE、fimH、ihA）通常与 F4 和 F18 菌毛相关。除了 tetC、sfa/focDE 和 ompT 之外，ARG 和 VG 之间的关联很少是明显的，对于 O141 分离物的子集，这表明可能从 ExPEC 获得质粒。多重耐药性 ETEC ARG/VG 谱表明存在相当大的菌株和质粒多样性的可能性很高，这反映了个体农场层面的各种选择压力，而不是 MDR 耐药性/毒性克隆的出现和横向传播。

       This study aimed to characterize antimicrobial resistance and virulence genes in multi-drug resistant enterotoxigenic Escherichia coli (ETEC) isolates (n = 117) collected from porcine post-weaning diarrhoea cases in Australia (1999–2005). Isolates were serotyped, antibiogram-phenotyped for 12 antimicrobial agents and genotyped by PCR for 30 plasmid-mediated antimicrobial resistance genes (ARGs), 22 intestinal and 38 extraintestinal E. coli virulence genes (VGs). Nine serogroups were identified, the most prevalent being O149 (46.2%), O141 (11.2%) and Ont (31.6%). None of the isolates showed resistance to ceftiofur or enrofloxacin and 9.4% were resistant to florfenicol. No corresponding extended-spectrum/AmpC β-lactamase, fluoroquinolone or floR ARGs were detected. An antimicrobial resistance index (ARI) was calculated from the combined data with a weighting for each antimicrobial agent dependent upon its significance to human health. Serogroup O141 isolates had a significantly higher ARI due to an elevated prevalence of aminoglycoside ARGs and possession of more virulence genes (VGs), including ExPEC or EHEC adhesins (bmaE, sfa/focDE, fimH, ihA) in toxin-producing strains that lacked the normally associated F4 and F18 fimbriae. Few associations between ARGs and VGs were apparent, apart from tetC, sfa/focDE and ompT which, for a sub-set of O141 isolates, suggest possible plasmid acquisition from ExPEC. The multi-drug resistant ETEC ARG/VG profiles indicate a high probability of considerable strain and plasmid diversity, reflecting various selection pressures at the individual farm level rather than emergence and lateral spread of MDR resistant/virulent clones.

https://www.sciencedirect.com/science/article/pii/S0378113510001859