{"title":"Mutations in the pmrB gene constitute the major mechanism underlying chromosomally encoded colistin resistance in clinical Escherichia coli","authors":"","doi":"10.1016/j.jgar.2024.06.013","DOIUrl":null,"url":null,"abstract":"<div><h3>Objectives</h3><p>The mechanisms underlying chromosomally encoded colistin resistance in <em>Escherichia coli</em> remain insufficiently investigated. In this study, we investigated the contribution of various <em>pmrB</em> mutations from <em>E. coli</em> clinical isolates to colistin resistance.</p></div><div><h3>Methods</h3><p>The resistance mechanisms in eight <em>mcr</em>-negative colistin-resistant <em>E. coli</em> 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 <em>pmrA</em> and <em>pmrK</em> (which are part of the <em>pmrCAB</em> and <em>pmrHFIJKLM</em> operons associated with colistin resistance) were measured using reverse transcription-quantitative real-time polymerase chain reaction.</p></div><div><h3>Results</h3><p>In the complementation experiments, various mutated <em>pmrB</em> alleles from the eight <em>mcr</em>-negative colistin-resistant <em>E. coli</em> 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 <em>pmrA</em> and <em>pmrK</em> 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.</p></div><div><h3>Conclusions</h3><p>Colistin resistance mediated by amino acid substitutions in PmrB is a major chromosomally encoded mechanism in <em>E. coli</em> of clinical origin.</p></div>","PeriodicalId":15936,"journal":{"name":"Journal of global antimicrobial resistance","volume":null,"pages":null},"PeriodicalIF":3.7000,"publicationDate":"2024-07-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.sciencedirect.com/science/article/pii/S2213716524001231/pdfft?md5=b1f5d54d4b0a2ef910c7bd7fb1e956ad&pid=1-s2.0-S2213716524001231-main.pdf","citationCount":"0","resultStr":null,"platform":"Semanticscholar","paperid":null,"PeriodicalName":"Journal of global antimicrobial resistance","FirstCategoryId":"3","ListUrlMain":"https://www.sciencedirect.com/science/article/pii/S2213716524001231","RegionNum":3,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":null,"EPubDate":"","PubModel":"","JCR":"Q2","JCRName":"INFECTIOUS DISEASES","Score":null,"Total":0}
引用次数: 0
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.
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.