School of Laboratory Medicine and Life Sciences, Wenzhou Medical University, Wenzhou, Zhejiang, China.
Department of Clinical Laboratory, The First Affiliated Hospital of Wenzhou Medical University, Wenzhou, Zhejiang, China.
J Antibiot (Tokyo). 2020 Sep;73(9):636-641. doi: 10.1038/s41429-020-0306-5. Epub 2020 Apr 27.
In this study, we report a clinical isolate of a carbapenem-, colistin-, and fosfomycin-resistant Escherichia coli isolate DC-3737 co-harboring bla, mcr-1, and fosA3 from an inpatient in China. Antimicrobial susceptibility testing, polymerase chain reaction, multi-locus sequence typing, conjugation experiment, and Southern blot hybridization were performed on E. coli DC-3737 isolated from the wound. Plasmid analysis is presented and the locations of bla, mcr-1, fosA3, and other resistance genes were identified as well. E. coli DC-3737 was resistant to ampicillin, ceftriaxone, ceftazidime, ciprofloxacin, levofloxacin, gentamicin, tobramycin, trimethoprim-sulfamethoxazole, imipenem, meropenem, ertapenem, fosfomycin and colistin, and with intermediate susceptibility to amikacin. It was typed as sequence type 27. The isolate possessed bla, mcr-1, fosA3, bla, bla, aac (6')-Ib-cr and sul1 simultaneously. In addition, the mutations in quinolone resistance-determinant regions (QRDRs) such as Ser83Leu and Asp87Asn in gyrA, and Ser80Ile in parC were detected. Conjugation assays revealed that bla, fosA3, sul1, mcr-1, and bla genes could successfully transfer their resistance phenotype to E. coli strain J53. Plasmid analysis and Southern hybridization showed that DC-3737 possessed Z-type self-transmissible plasmid bearing bla, fosA3, and sul1. Moreover, mcr-1, bla, and bla were located on a ~60-kb IncFIB type self-transmissible plasmid. This is the first report of bla, mcr-1 and fosA3 co-harboring in E. coli in China. Moreover, it is also the first description of the co-harboring of bla and fosA3 in a single Z plasmid in Enterobacteriaceae species. The identification of E. coli DC-3737 co-harboring bla, mcr-1, and fosA3 in this study highlights the need to increase epidemiologic surveillance and the need for new classes of antibiotics to address multidrug-resistant bacteria.
在这项研究中，我们报告了一例来自中国住院患者的携带 bla、mcr-1 和 fosA3 的碳青霉烯类、黏菌素类和磷霉素类耐药的大肠杆菌临床分离株 DC-3737。对从伤口中分离出的大肠杆菌 DC-3737 进行了药敏试验、聚合酶链反应、多位点序列分型、接合实验和 Southern 印迹杂交。提出了质粒分析，并确定了 bla、mcr-1、fosA3 和其他耐药基因的位置。大肠杆菌 DC-3737 对氨苄西林、头孢曲松、头孢他啶、环丙沙星、左氧氟沙星、庆大霉素、妥布霉素、复方磺胺甲噁唑、亚胺培南、美罗培南、厄他培南、磷霉素和黏菌素耐药，对阿米卡星中介。它被分型为 27 型。该分离株同时携带 bla、mcr-1、fosA3、bla、bla、aac（6'）-Ib-cr 和 sul1。此外，还检测到 gyrA 中喹诺酮耐药决定区（QRDRs）的突变，如 Ser83Leu 和 Asp87Asn，以及 parC 中的 Ser80Ile。接合试验表明，bla、fosA3、sul1、mcr-1 和 bla 基因可以成功地将其耐药表型转移到大肠杆菌 J53 株。质粒分析和 Southern 杂交表明，DC-3737 携带 bla、fosA3 和 sul1 的 Z 型可自我传递质粒。此外，mcr-1、bla 和 bla 位于一个约 60kb 的 IncFIB 型可自我传递质粒上。这是中国首次报道 bla、mcr-1 和 fosA3 共存在大肠杆菌中。此外，这也是首次描述肠杆菌科物种中单个 Z 质粒共携带 bla 和 fosA3。本研究中鉴定出的大肠杆菌 DC-3737 同时携带 bla、mcr-1 和 fosA3，这凸显了增加流行病学监测和开发新类抗生素以解决多药耐药菌的必要性。
