Mutations in the pmrB gene constitute the major mechanism underlying chromosomally encoded colistin resistance in clinical Escherichia coli

IF 3.7 3区 医学 Q2 INFECTIOUS DISEASES
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Abstract

Objectives

The mechanisms underlying chromosomally encoded colistin resistance in Escherichia coli remain insufficiently investigated. In this study, we investigated the contribution of various pmrB mutations from E. coli clinical isolates to colistin resistance.

Methods

The resistance mechanisms in eight mcr-negative colistin-resistant E. coli isolates obtained from a nationwide surveillance program in Taiwan using recombinant DNA techniques and complementary experiments were investigated. The minimal inhibitory concentrations (MICs) of colistin in the recombinant strains were compared with those in the parental strains. The expression levels of pmrA and pmrK (which are part of the pmrCAB and pmrHFIJKLM operons associated with colistin resistance) were measured using reverse transcription-quantitative real-time polymerase chain reaction.

Results

In the complementation experiments, various mutated pmrB alleles from the eight mcr-negative colistin-resistant E. coli strains were introduced into an ATCC25922 mutant with a PmrB deletion, which resulted in colistin resistance. The MIC levels of colistin in the most complemented strains were comparable to those of the parental colistin-resistant strains. Increased expression levels of pmrA and pmrK were consistently detected in most complemented strains. The impact for colistin resistance was confirmed for various novel amino acid substitutions, P94L, G19E, L194P, L98R and R27L in PmrB from the parental clinical strains. The detected amino acid substitutions are distributed in the different functional domains of PmrB.

Conclusions

Colistin resistance mediated by amino acid substitutions in PmrB is a major chromosomally encoded mechanism in E. coli of clinical origin.

pmrB 基因突变是临床大肠杆菌对染色体编码的可乐定产生抗药性的主要机制。
目的:对大肠埃希菌染色体编码的可乐定耐药性机制的研究仍然不足。本研究调查了大肠埃希菌临床分离株中各种 pmrB 突变对大肠菌素耐药性的贡献:方法:采用重组 DNA 技术和互补实验,研究了从台湾全国性监测项目中获得的 8 株 mcr 阴性耐大肠菌素大肠杆菌的耐药机制。将重组菌株与亲本菌株的可乐定最小抑菌浓度(MICs)进行了比较。利用反转录-实时定量聚合酶链反应测定了 pmrA 和 pmrK(与可乐定抗性相关的 pmrCAB 和 pmrHFIJKLM 操作子的一部分)的表达水平:结果:在互补实验中,将 8 株 mcr 阴性的耐大肠菌株中各种突变的 pmrB 等位基因导入 PmrB 缺失的 ATCC25922 突变体中,从而产生了对大肠菌素的耐药性。在大多数互补菌株中,可乐定的 MIC 水平与亲本可乐定耐药菌株相当。在大多数互补菌株中都检测到 pmrA 和 pmrK 表达水平的升高。来自亲本临床菌株的 PmrB 中的 P94L、G19E、L194P、L98R 和 R27L 等多个新型氨基酸置换对秋水仙素耐药性的影响得到了证实。检测到的氨基酸置换分布在 PmrB 的不同功能域:结论:由 PmrB 氨基酸置换介导的秋水仙碱耐药性是临床来源大肠杆菌的一种主要染色体编码机制。
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来源期刊
Journal of global antimicrobial resistance
Journal of global antimicrobial resistance INFECTIOUS DISEASES-PHARMACOLOGY & PHARMACY
CiteScore
8.70
自引率
2.20%
发文量
285
审稿时长
34 weeks
期刊介绍: The Journal of Global Antimicrobial Resistance (JGAR) is a quarterly online journal run by an international Editorial Board that focuses on the global spread of antibiotic-resistant microbes. JGAR is a dedicated journal for all professionals working in research, health care, the environment and animal infection control, aiming to track the resistance threat worldwide and provides a single voice devoted to antimicrobial resistance (AMR). Featuring peer-reviewed and up to date research articles, reviews, short notes and hot topics JGAR covers the key topics related to antibacterial, antiviral, antifungal and antiparasitic resistance.
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