Zhao Lina, Zhang Jing, Zheng Beiwen, Wei Zeqing, Shen Ping, Li Sujuan, Li Lanjuan, Xiao Yonghong
State Key Laboratory for Diagnosis and Treatment of Infectious Diseases, The First Affiliated Hospital, College of Medicine, Zhejiang University, Hangzhou, China; Collaborative Innovation Center for Diagnosis and Treatment of Infectious Diseases, Hangzhou, China.
State Key Laboratory for Diagnosis and Treatment of Infectious Diseases, The First Affiliated Hospital, College of Medicine, Zhejiang University, Hangzhou, China; Collaborative Innovation Center for Diagnosis and Treatment of Infectious Diseases, Hangzhou, China
J Clin Microbiol. 2015 Mar;53(3):766-70. doi: 10.1128/JCM.02594-14. Epub 2014 Dec 17.
The high frequency of fluoroquinolone resistance in Escherichia coli is a feature of clinical bacteriology in China, where the molecular epidemiology and genetic characteristics of this resistance in county hospitals remain unclear. A total of 590 nonduplicate E. coli isolates from 30 county hospitals located across seven Chinese regions were examined for plasmid-mediated quinolone resistance (PMQR) genes and mutations in quinolone resistance-determining regions (QRDRs). Multilocus sequence typing (MLST) and phylogenetic analysis of fluoroquinolone-resistant isolates were used to determine their genetic relatedness. The ciprofloxacin resistance rate of community-onset E. coli was 51.2%, and at least one PMQR gene was carried by 220 (37.3%) isolates. These included qnr (3.7%), aac(6')-Ib-cr (19.7%), qepA (14.4%), and oqxAB (3.8%). Two novel oqxB mutants were identified and named oqxB20 and oqxB29. From 60 sequence types (STs) isolated, 5 novel STs (ST4499 to ST4503) were identified. ST1193 (7.9%) was the second most abundant ST among fluoroquinolone-resistant isolates (ST131 was the most common, with 14.6%), and this is the first report of it in China. This is also the first report of ST2115 and ST3014 isolates from human samples. Ciprofloxacin-resistant E. coli isolates fell mainly into phylogroups B2 and D. The rates of fluoroquinolone resistance and the prevalence of PMQR genes in community-onset E. coli isolates from Chinese county hospitals were high. The wide-ranging molecular epidemiology of E. coli isolates from scattered locations across China indicates that fluoroquinolone resistance evolved from different sources.
大肠杆菌中氟喹诺酮耐药性的高频率是中国临床细菌学的一个特征，而县级医院中这种耐药性的分子流行病学和遗传特征仍不清楚。对来自中国七个地区30家县级医院的590株非重复大肠杆菌分离株进行了质粒介导喹诺酮耐药性（PMQR）基因检测以及喹诺酮耐药决定区（QRDRs）的突变检测。对氟喹诺酮耐药分离株进行多位点序列分型（MLST）和系统发育分析，以确定它们的遗传相关性。社区获得性大肠杆菌的环丙沙星耐药率为51.2%，220株（37.3%）分离株携带至少一种PMQR基因。这些基因包括qnr（3.7%）、aac(6')-Ib-cr（19.7%）、qepA（14.4%）和oqxAB（3.8%）。鉴定出两个新型oqxB突变体，命名为oqxB20和oqxB29。在分离出的60种序列类型（STs）中，鉴定出5种新型STs（ST4499至ST4503）。ST1193（7.9%）是氟喹诺酮耐药分离株中第二常见的ST（最常见的是ST131，占14.6%），这是其在中国的首次报道。这也是来自人类样本的ST2115和ST3014分离株的首次报道。环丙沙星耐药大肠杆菌分离株主要属于B2和D系统发育群。中国县级医院社区获得性大肠杆菌分离株的氟喹诺酮耐药率和PMQR基因流行率较高。来自中国各地分散地点的大肠杆菌分离株广泛的分子流行病学表明，氟喹诺酮耐药性是由不同来源演变而来的。
