背景：
在环境水中产生超广谱β-内酰胺酶（ESBLs）的大肠杆菌（E.coli）分离株逐渐成为对公众健康的潜在威胁，而关于产生ESBL的大肠杆菌分离株在河流和湖泊中的详细信息。中国西北地区稀缺。在本研究中，其目的是表征从中国西北地区水域分离的产ESBL的大肠杆菌。

结果：
从中国西北地区的11个河流和湖泊中共获得2686株大肠杆菌，筛选出ESBL生产者。 76个（2.8％）分离株被分类为ESBL生产者，系统发育组D和A占ESBL生产者的59.2％。 CTX-Ms是主要的ESBLs基因型，它们由7种blaCTX-M亚型代表。 blaCTX-M-14是最常见的特异性CTX-M基因，其次是blaCTX-M-9，blaCTX-M-123，blaCTX-M-15，blaCTX-M-27，blaCTX-M-1和blaCTX-M -65。此外，76位ESBL生产者中有54位携带至少一种质粒介导的喹诺酮抗性（PMQR）基因，而aac（6'） - Ib-cr占优势。毒力因子的总体发生率为1.3％（eae）至48.7％（traT）。在76个ESBL生产者中确认了37种序列类型（STs），其中主要是ST10，其由10个分离株代表;重要的是，检测到与人和动物严重感染相关的克隆B2-ST131三次。

结论：
中国西北地区河流和湖泊产ESBL的大肠杆菌的流行率较低（2.8％），根据毒力因子谱最常检测出肠外致病性大肠杆菌（ExPEC）致病型。 76.3％的ESBL生产者携带超过一种β-内酰胺酶基因，而blaCTX-M-14是主要的基因型。值得注意的是，来自高根运河的一株ST131分离株同时携带blaCTX-M-9，blaCTX-M-15，blaCTX-M-123，blaKPC-2，blaNDM-1，blaOXA-2以及PMQR基因qnrA，qnrS和aac （6' ） - 的Ib-CR。

BACKGROUND:
Extended-spectrum β-lactamases (ESBLs)-producing Escherichia coli (E. coli) isolates in environment water become progressively a potential threat to public health, while the detailed information about the ESBL-producing E. coli isolates in the rivers and lakes in Northwest China is scarce. In the present study, it was aimed to characterize the ESBL-producing E. coli isolated from the surface waters in Northwest China.

RESULTS:
A total of 2686 E. coli isolates were obtained from eleven rivers and lakes in Northwest China to screen for ESBL producers. Seventy-six (2.8%) isolates were classified as ESBL producers, and phylogenic groups D and A accounted for 59.2% of the ESBL producers. CTX-Ms were the predominant ESBLs genotype, and they were represented by seven blaCTX-M subtypes. blaCTX-M-14 was the most prevalent specific CTX-M gene, followed by blaCTX-M-9, blaCTX-M-123, blaCTX-M-15, blaCTX-M-27, blaCTX-M-1 and blaCTX-M-65. Moreover, 54 of the 76 ESBL producers carried at least one plasmid-mediated quinolone resistance (PMQR) gene, and aac(6')-Ib-cr was predominant. The overall occurrence of virulence factors ranged from 1.3% (eae) to 48.7% (traT). Thirty-seven sequence types (STs) were confirmed among the 76 ESBL producers, and the predominant was ST10, which was represented by 10 isolates; importantly, clone B2-ST131, associated with severe infections in humans and animals, was detected three times.

CONCLUSION:
The prevalence of ESBL-producing E. coli from the rivers and lakes in Northwest China was low (2.8%), and the extraintestinal pathogenic E. coli (ExPEC) pathotype was the most commonly detected on the basis of the virulence factor profiles. 76.3% of ESBL producers harbored more than one β-lactamase gene, and blaCTX-M-14 was the predominant genotype. Notably, one ST131 isolate from Gaogan Canal simultaneously harbored blaCTX-M-9, blaCTX-M-15, blaCTX-M-123, blaKPC-2, blaNDM-1, blaOXA-2 as well as the PMQR genes qnrA, qnrS and aac(6')-Ib-cr.

https://www.ncbi.nlm.nih.gov/pubmed/30286725