Liu Xiaoqiang, Liu Haixia, Wang Le, Peng Qian, Li Yinqian, Zhou Hongchao, Li Qinfan
Department of Basic Veterinary, College of Veterinary Medicine, Northwest A&F University, Yangling, China.
Front Microbiol. 2018 Aug 3;9:1756. doi: 10.3389/fmicb.2018.01756. eCollection 2018.
The aim of the present study was to explore the prevalence and molecular characterization of extended-spectrum β-lactamase (ESBL)-producing collected from pig farms in Northwest China. Between May 2015 and June 2017, a total of 456 isolates were collected from fecal samples of healthy and diarrheal pigs in Northwest China to screen the ESBL producers. The β-lactamases, plasmid-mediated quinolone resistance (PMQR) genes and virulence genes among ESBL producers were corroborated by PCR and sequencing. Finally, ESBL producers were further grouped according to phylogenetic background and genetic relatedness. Forty-four (9.6%) out of the 456 isolates were identified as ESBL-producing isolates. All ESBL producers exhibited multidrug resistance (MDR) phenotype, and more than 90% of the ESBL producers were resistant to amoxicillin, amoxicillin-clavulanic acid, oxytetracycline, enrofloxacin and sulfamethoxazole/trimethoprim. All ESBL producers harbored at least one type of β-lactamase, with , , , , and being detected in forty, thirty, seven, four, two and one isolates, respectively. Sequencing revealed the most common subtype was ( = 24), followed by ( = 14), ( = 11), ( = 10) and ( = 9). ( = 23) was the predominant PMQR gene, and all PMQR genes were detected in co-existence with β-lactamase genes. ( = 18) and F4 ( = 18) were the most prevalent enterotoxin and fimbrial adhesin, respectively, and 27 different virotypes were found with respect to the association of enterotoxins and fimbrial adhesins. Twenty-four different sequence types (STs) were identified among 44 ESBL producers, and clones ST405, ST10 and ST648 were strongly present in more than one-third (34.1%) of ESBL producers. All ESBL-producing isolates exhibited MDR phenotype, and showed high prevalence of β-lactamase and PMQR genes. Especially, one isolate harbored ESBL genes , , , , , and carbapenemase gene and , as well as PMQR genes and .
本研究的目的是探索中国西北地区猪场产超广谱β-内酰胺酶（ESBL）菌株的流行情况及其分子特征。2015年5月至2017年6月，共从中国西北地区健康猪和腹泻猪的粪便样本中收集了456株大肠杆菌分离株，以筛选产ESBL菌株。通过PCR和测序对产ESBL菌株中的β-内酰胺酶、质粒介导的喹诺酮耐药性（PMQR）基因和毒力基因进行了确证。最后，根据系统发育背景和遗传相关性对产ESBL菌株进行了进一步分组。456株大肠杆菌分离株中有44株（9.6%）被鉴定为产ESBL菌株。所有产ESBL菌株均表现出多重耐药（MDR）表型，超过90%的产ESBL菌株对阿莫西林、阿莫西林-克拉维酸、土霉素、恩诺沙星和磺胺甲恶唑/甲氧苄啶耐药。所有产ESBL菌株均携带至少一种类型的β-内酰胺酶，分别在40株、30株、7株、4株、2株和1株分离株中检测到blaCTX-M、blaTEM、blaSHV、blaOXA-1、blaOXA-2和blaOXA-10。测序显示最常见的blaCTX-M亚型是blaCTX-M-14（n = 24），其次是blaCTX-M-15（n = 14）、blaCTX-M-27（n = 11）、blaCTX-M-9（n = 10）和blaCTX-M-2（n = 9）。qnrS（n = 23）是主要的PMQR基因，所有PMQR基因均与β-内酰胺酶基因共存。elt（n = 18）和F4（n = 18）分别是最常见的肠毒素和菌毛黏附素，关于肠毒素和菌毛黏附素的关联发现了27种不同的毒力型。在44株产ESBL菌株中鉴定出24种不同的序列类型（STs），克隆ST405、ST10和ST648在超过三分之一（34.1%）的产ESBL菌株中大量存在。所有产ESBL的大肠杆菌分离株均表现出MDR表型，并且β-内酰胺酶和PMQR基因的流行率很高。特别是，一株分离株携带ESBL基因blaCTX-M-14、blaTEM-1、blaSHV-12、blaOXA-1、blaOXA-2、blaOXA-10和碳青霉烯酶基因blaKPC-2和blaNDM-1，以及PMQR基因qnrS和aac(6’)-Ib-cr。
