摘要

脂肽类抗生素达托霉素（DAP）是抗严重肠球菌感染的关键药物，但在临床环境中出现耐药性是一个主要问题。 LiaFSR系统在肠球菌DAP耐药性（DAP-R）的发展中起着重要作用，并且已经提出阻断该应激反应系统作为新的治疗策略。在这项工作中，我们确定了粪肠球菌中不依赖LiaR的途径，这些途径调节细胞膜对抗生素的适应性。我们将缺乏liaR的粪肠球菌OG1RF（一种实验室菌株）和S613TM（一种临床菌株）用于增加DAP浓度，导致DAP-R的发展和MIC对杆菌肽和头孢曲松的升高。全基因组测序鉴定了YxdJK双组分调节系统和DAP-R两种菌株中推定的脂肪酸激酶（dak）的变化。在DAP-R突变体和野生型OG1RF中编码YxdJ反应调节因子的基因的缺失使得MIC降低至DAP，即使存在功能性LiaFSR系统也是如此。 dak突变与生长缓慢，膜流动性降低和细胞形态改变有关。这些发现表明重叠的应激反应途径可以提供针对粪肠球菌中的抗微生物肽的保护，其在细菌适应性方面具有显着成本。本文受版权保护。版权所有。

The lipopeptide antibiotic daptomycin (DAP) is a key drug against serious enterococcal infections, but emergence of resistance in the clinical setting is a major concern. The LiaFSR system plays a prominent role in the development of DAP resistance (DAP-R) in enterococci, and blocking this stress response system has been proposed as a novel therapeutic strategy. In this work, we identify LiaR-independent pathways in E. faecalis that regulate cell membrane adaptation in response to antibiotics. We adapted E. faecalis OG1RF (a laboratory strain) and S613TM (a clinical strain) lacking liaR to increasing concentrations of DAP, leading to the development of DAP-R and elevated MICs to bacitracin and ceftriaxone. Whole genome sequencing identified changes in the YxdJK two-component regulatory system and a putative fatty acid kinase (dak) in both DAP-R strains. Deletion of the gene encoding the YxdJ response regulator in both the DAP-R mutant and wild type OG1RF decreased MICs to DAP, even when a functional LiaFSR system was present. Mutations in dak were associated with slower growth, decreased membrane fluidity and alterations of cell morphology. These findings suggest overlapping stress response pathways can provide protection against antimicrobial peptides in E. faecalis at a significant cost in bacterial fitness. This article is protected by copyright. All rights reserved.

https://www.ncbi.nlm.nih.gov/pubmed/30582877