A comparison of virulence genes, antimicrobial resistance profiles and genetic diversity of avian pathogenic <i>Escherichia coli</i> (APEC) isolates from broilers and broiler breeders in Thailand and Australia

Avian pathogenic <i>Escherichia coli</i> (APEC) is the causative agent of colibacillosis resulting in economic losses in the poultry industry worldwide. A total of 168 APEC isolates, equal numbers from Australian and Thai broilers/broiler breeders, were identified and tested for their susceptibility to ten antimicrobial agents. Most of the Thai APEC isolates were multidrug-resistant (MDR) (60.7%) whilst Australian APEC isolates showed a MDR rate of just 10.7%. The Thai APEC isolates exhibited high resistance to tetracycline (TET) (84.5%), amoxicillin (AMX) (70.2%) and trimethoprim–sulfamethoxazole (SXT) (51.2%) whilst the Australian APEC isolates showed lower levels of resistance (TET 36.9%, AMX 29.8%, SXT 17.86%). The 34 Thai APEC and four Australian APEC isolates which were resistant to nalidixic acid were characterized for their carriage of mutations in the quinolone resistance determining region of <i>gyrA</i>, <i>gyrB</i>, <i>parC</i> and <i>parE</i>. While no mutations were detected in <i>gyrB</i> in the Thai isolates, the Ser83Leu and Asp87Asn substitutions in <i>gyrA</i> and Ser80Ile in <i>parC</i> were common (<i>n</i> = 9/34). In regard to the Australian isolates, the Ser83Leu and Asp678Glu substitution in <i>gyrA</i>, Pro385Ala and Ser492Asn in <i>gyrB</i> and Met241Ile and Asp475Glu in <i>parC</i> were identified (<i>n </i>= 3/4). Rep-PCR analysis of the 84 Thai and 84 Australian APEC isolates showed 16 main clusters that mostly contained isolates from both countries. Our results suggest that the emergence of MDR is a major concern for the Thai APEC isolates and that more prudent use of antimicrobial agents in Thai poultry production is required.

禽致病性大肠杆菌（Avian pathogenic Escherichia coli, APEC）是引发大肠杆菌病的病原菌，该病害在全球范围内给家禽养殖业造成经济损失。本研究共鉴定得到168株APEC分离株，其中来自澳大利亚与泰国肉鸡及肉种鸡的分离株数量各占一半，随后对其开展10种抗菌药物的药敏敏感性测试。泰国APEC分离株中多数为多重耐药（multidrug-resistant, MDR）菌株，耐药率达60.7%；而澳大利亚APEC分离株的多重耐药率仅为10.7%。泰国APEC分离株对四环素（tetracycline, TET）、阿莫西林（amoxicillin, AMX）以及甲氧苄啶-磺胺甲恶唑（trimethoprim–sulfamethoxazole, SXT）的耐药率分别高达84.5%、70.2%和51.2%；澳大利亚APEC分离株的耐药水平则相对较低，对应耐药率分别为36.9%、29.8%和17.86%。针对34株泰国APEC和4株澳大利亚APEC的萘啶酸耐药株，本研究对其携带的*gyrA*、*gyrB*、*parC*及*parE*基因的喹诺酮耐药决定区突变情况进行了表征。在泰国分离株中，未在*gyrB*基因中检测到突变，但*gyrA*的Ser83Leu与Asp87Asn突变以及*parC*的Ser80Ile突变较为常见（n=9/34）。对于澳大利亚分离株，研究检测到*gyrA*的Ser83Leu与Asp678Glu突变、*gyrB*的Pro385Ala与Ser492Asn突变，以及*parC*的Met241Ile与Asp475Glu突变（n=3/4）。对84株泰国与84株澳大利亚APEC分离株开展重复序列聚合酶链反应（Rep-PCR）分析，结果显示共形成16个主要聚类簇，其中多数聚类簇同时包含来自两国的分离株。本研究结果表明，多重耐药菌株的出现对泰国APEC分离株而言是一项主要关注点，泰国家禽生产中亟需更加审慎地使用抗菌药物。

搜集汇总

背景与挑战

背景概述

该数据集比较了泰国和澳大利亚禽致病性大肠杆菌（APEC）分离株的毒力基因、抗菌素耐药性谱和遗传多样性。研究发现，泰国APEC分离株的多重耐药性率显著高于澳大利亚分离株，且两国分离株在遗传聚类上存在交叉。这突出了APEC耐药性问题的地域差异，并强调了在泰国家禽生产中更谨慎使用抗菌剂的必要性。