Department of Clinical Laboratory, The Second Affiliated Hospital and Yuying Children's Hospital of Wenzhou Medical University, 109 Xueyuan W Road, Wenzhou 325000, Zhejiang Province, China; Department of Clinical Laboratory, The First Affiliated Hospital of Nanchang University, Nanchang, Jiangxi Province, China.
Department of Clinical Laboratory, The Second Affiliated Hospital and Yuying Children's Hospital of Wenzhou Medical University, 109 Xueyuan W Road, Wenzhou 325000, Zhejiang Province, China.
J Glob Antimicrob Resist. 2020 Sep;22:238-243. doi: 10.1016/j.jgar.2019.12.019. Epub 2020 Feb 13.
Older antimicrobials such as fosfomycin are being considered as alternative agents in the treatment of drug-resistant organisms. However, there are limited data on the usefulness of fosfomycin against carbapenem-resistant Klebsiella pneumoniae (CRKP). This study aimed to investigate the prevalence of fosfomycin resistance and associated mechanisms in CRKP.
A total of 99 clinical CRKP isolates were collected in the Second Affiliated Hospital of Wenzhou Medical University (Wenzhou, China) between January 2017 and June 2018. Fosfomycin susceptibility testing was performed by the agar dilution method. Carbapenemase and fosfomycin resistance genes were detected by PCR. Analysis of the murA, glpT, uhpT, uhpA, ptsI and cyaA genes was performed by PCR and sequencing of four fosfomycin-resistant fosA3-negative CRKP strains. Conjugation experiments were employed to determine the mobility of the fosA3 gene.
Of the 99 CRKP isolates, fosfomycin-non-susceptibility was detected in 48 (48.5%) isolates, among which the fosA3 gene was detected in 44. Among the four fosfomycin-resistant fosA3-negative CRKP isolates, one isolate possessed a single nucleotide insertion and deletion mutations as well as 219 nucleotide substitution mutations in murA, two isolates possessed deletion or mutation of large DNA fragments in glpT, and one isolate possessed a fragment insertion sequence in glpT. Transfection into Escherichia coli J53 via plasmid conjugation was successful for 19 (43.2%) of the 44 fosA3-positive CRKP isolates.
The fosA3 gene is the primary mechanism of fosfomycin resistance in CRKP and can be transmitted widely by plasmid in hospitals. Mutations in murA and glpT were found in fosfomycin-resistant fosA3-negative CRKP.
诸如磷霉素等较老的抗生素正被视为治疗耐药菌的替代药物。然而，关于磷霉素对耐碳青霉烯类肺炎克雷伯菌（CRKP）的有效性的数据有限。本研究旨在调查 CRKP 中磷霉素耐药的流行情况及其相关机制。
本研究共收集了 2017 年 1 月至 2018 年 6 月期间在温州医科大学附属第二医院（温州，中国）的 99 株临床 CRKP 分离株。采用琼脂稀释法进行磷霉素药敏试验。通过 PCR 检测碳青霉烯酶和磷霉素耐药基因。通过 PCR 和测序分析 4 株磷霉素耐药但 fosA3 阴性的 CRKP 株的 murA、glpT、uhpT、uhpA、ptsI 和 cyaA 基因。采用接合实验来确定 fosA3 基因的移动性。
在 99 株 CRKP 分离株中，48 株（48.5%）对磷霉素表现为非敏感性，其中 44 株检测到 fosA3 基因。在 4 株磷霉素耐药但 fosA3 阴性的 CRKP 分离株中，1 株 murA 基因发生单个核苷酸插入和缺失突变以及 219 个核苷酸取代突变，2 株 glpT 基因发生大片段缺失或突变，1 株 glpT 基因发生插入序列片段。通过质粒接合将 fosA3 阳性的 44 株 CRKP 分离株中的 19 株（43.2%）转染到大肠杆菌 J53 中是成功的。
fosA3 基因是 CRKP 中磷霉素耐药的主要机制，并且可以通过质粒在医院中广泛传播。在磷霉素耐药但 fosA3 阴性的 CRKP 中发现 murA 和 glpT 突变。
