Division of Infectious Diseases, Department of Medicine II, Medical Centre and Faculty of Medicine, University of Freiburg, Freiburg, Germany
Division of Infectious Diseases, Department of Medicine II, Medical Centre and Faculty of Medicine, University of Freiburg, Freiburg, Germany.
Antimicrob Agents Chemother. 2021 Mar 18;65(4). doi: 10.1128/AAC.01735-20.
Gram-negative bacteria partly rely on efflux pumps to facilitate growth under stressful conditions and to increase resistance to a wide variety of commonly used drugs. In recent years, sequence type 131 (ST131) has emerged as a major cause of extraintestinal infection frequently exhibiting a multidrug resistance (MDR) phenotype. The contribution of efflux to MDR in emerging MDR clones, however, is not well studied. We characterized strains from an international collection of clinical MDR isolates by MIC testing with and without the addition of the AcrAB-TolC efflux inhibitor 1-(1-naphthylmethyl)-piperazine (NMP). MIC data for 6 antimicrobial agents and their reversion by NMP were analyzed by principal-component analysis (PCA). PCA revealed a group of 17 MDR isolates ( = 34) exhibiting increased susceptibility to treatment with NMP, suggesting an enhanced contribution of efflux pumps to antimicrobial resistance in these strains (termed enhanced efflux phenotype [EEP] strains). Only 1/17 EEP strains versus 12/17 non-EEP MDR strains belonged to the ST131 clonal group. Whole-genome sequencing revealed marked differences in efflux-related genes between EEP and control strains, with the majority of notable amino acid substitutions occurring in AcrR, MarR, and SoxR. Quantitative reverse transcription-PCR (qRT-PCR) of multiple efflux-related genes showed significant overexpression of the AcrAB-TolC system in EEP strains, whereas in the remaining strains, we found enhanced expression of alternative efflux proteins. We conclude that a proportion of MDR strains exhibit an EEP, which is linked to an overexpression of the AcrAB-TolC efflux pump and a distinct array of genomic variations. Members of ST131, although highly successful, are less likely to exhibit the EEP.
革兰氏阴性菌部分依靠外排泵在应激条件下促进生长，并增加对各种常用药物的耐药性。近年来，131 型序列（ST131）已成为引起肠外感染的主要原因，常表现出多种药物耐药（MDR）表型。然而，外排泵对新兴 MDR 克隆的 MDR 贡献尚未得到很好的研究。我们通过添加或不添加 AcrAB-TolC 外排抑制剂 1-（1-萘基甲基）-哌嗪（NMP），用 MIC 试验对来自国际临床 MDR 分离株的菌株进行了特征描述。用主成分分析（PCA）分析了 6 种抗菌药物的 MIC 数据及其被 NMP 逆转的情况。PCA 显示出一组 17 株 MDR 分离株（=34）对 NMP 治疗的敏感性增加，表明这些菌株中外排泵对抗菌药物耐药性的贡献增强（称为增强型外排表型[EEP]菌株）。只有 1/17 EEP 株而非 17/17 非 EEP MDR 株属于 ST131 克隆群。全基因组测序显示 EEP 和对照菌株之间在与外排相关的基因方面存在显著差异，大多数显著的氨基酸取代发生在 AcrR、MarR 和 SoxR 中。多个与外排相关的基因的定量逆转录-PCR（qRT-PCR）显示 EEP 菌株中 AcrAB-TolC 系统的过度表达，而在其余菌株中，我们发现替代外排蛋白的表达增强。我们得出结论，一部分 MDR 菌株表现出 EEP，这与 AcrAB-TolC 外排泵的过度表达和一系列独特的基因组变异有关。尽管 ST131 成员非常成功，但它们不太可能表现出 EEP。
