在突尼斯患有大肠杆菌病的肉鸡中，mcr-1 介导的多粘菌素耐药性和β-内酰胺酶编码基因共存于多重耐药性大肠杆菌中。
Co-occurrence of mcr-1 mediated colistin resistance and β-lactamase-encoding genes in multidrug-resistant Escherichia coli from broiler chickens with colibacillosis in Tunisia.
机构信息
Manouba University, ISBST, BVBGR-LR11ES31, Biotechpole Sidi Thabet, Ariana, Tunisia; University of Tunis El Manar, Farhat Hached El Manar Campus - B.P. 94, Rommana City, Tunis, Tunisia.
Manouba University, ISBST, BVBGR-LR11ES31, Biotechpole Sidi Thabet, Ariana, Tunisia.
出版信息
J Glob Antimicrob Resist. 2020 Sep;22:538-545. doi: 10.1016/j.jgar.2020.03.017. Epub 2020 Apr 3.
OBJECTIVES
Colibacillosis caused by avian pathogenic Escherichia coli (APEC) is considered a major hindrance in poultry farming worldwide. This study aimed to characterize the genetic content and the relatedness between multidrug-resistant E. coli isolates from broiler chickens died due to colibacillosis from three farms from Tunisia.
METHODS
One hundred samples were collected from chickens' fresh carcasses from three poultry farms in Tunisia. E. coli isolation and identification were performed. Then, antimicrobial susceptibility regarding antibiotics, the ability to produce β-lactamases and minimum inhibitory concentration for colistin were determined according to Clinical and Laboratory Standards Institute guidelines. β-Lactam and non-β-lactam antimicrobial resistance genes, integrons, virulence genes, and phylogenetic groups were investigated using polymerase chain reaction. The genetic relatedness of the E. coli isolates was analysed by pulsed field gel electrophoresis (PFGE) and multilocus sequence typing (MLST).
RESULTS
A high infection rate of E. coli (50%) in infected organs of chickens was observed. The majority of E. coli isolates were multidrug resistant (96%); among them, 24% were colistin resistant and 30% were ESBL producing. Seven of 12 colistin-resistant isolates harboured the mcr-1 gene; among them, 10 were ESBL producing and carried bla, bla, and bla β-lactamase-encoding genes. E. coli isolates were assigned to different phylogroups but most of them (74%) belonged to the pathogenic phylogroup B2. Molecular typing by PFGE showed that some E. coli isolates harbouring ESBL-mcr-1 genes were clonally related. MLST revealed the presence of four different ST lineages among ESBL- and mcr-1-carrying E. coli: ST4187, ST3882; ST5693, and ST8932 with clonal dissemination of E. coli ST4187 between two of the farms.
CONCLUSION
This is the first report of ESBL-mcr-1-carrying E. coli isolates of a clinically relevant phylogenetic group (B2) from chickens that died due to colibacillosis in Tunisian poultry farms.
目的
由禽致病性大肠杆菌（APEC）引起的大肠杆菌病被认为是全球家禽养殖的主要障碍。本研究旨在分析来自突尼斯三个农场因大肠杆菌病死亡的肉鸡中分离的多重耐药大肠杆菌的遗传特征和相关性。
方法
从突尼斯三个家禽养殖场的鸡新鲜屠体中采集了 100 个样本。进行大肠杆菌的分离和鉴定。然后，根据临床和实验室标准协会的指南，确定抗生素的药敏性、β-内酰胺酶的产生能力以及粘菌素的最小抑菌浓度。使用聚合酶链反应（PCR）检测β-内酰胺类和非β-内酰胺类抗菌药物耐药基因、整合子、毒力基因和系统发育群。通过脉冲场凝胶电泳（PFGE）和多位点序列分型（MLST）分析大肠杆菌分离株的遗传相关性。
结果
在鸡感染器官中观察到大肠杆菌（50%）的高感染率。大多数大肠杆菌分离株呈多重耐药（96%）；其中 24%对粘菌素耐药，30%产 ESBL。12 株粘菌素耐药株中有 7 株携带 mcr-1 基因；其中 10 株产 ESBL，携带 bla、bla 和 blaβ-内酰胺酶编码基因。大肠杆菌分离株被分配到不同的菌群，但大多数（74%）属于致病性菌群 B2。PFGE 分子分型显示，一些携带 ESBL-mcr-1 基因的大肠杆菌分离株具有克隆相关性。MLST 显示，携带 ESBL 和 mcr-1 的大肠杆菌存在 4 种不同的 ST 谱系：ST4187、ST3882、ST5693 和 ST8932，其中大肠杆菌 ST4187 在两个农场之间呈克隆传播。
结论
这是首次在突尼斯家禽养殖场因大肠杆菌病死亡的鸡中报道具有临床相关系统发育群（B2）的产 ESBL-mcr-1 大肠杆菌分离株。
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