Department of Veterinary Disease Biology, Faculty of Health and Medical Sciences, University of Copenhagen, Frederiksberg C, Denmark.
Interdisciplinary Nanoscience Center, Aarhus University, Aarhus C, Denmark.
mBio. 2017 Sep 5;8(5):e01114-17. doi: 10.1128/mBio.01114-17.
is intrinsically resistant to polymyxins (polymyxin B and colistin), an important class of cationic antimicrobial peptides used in treatment of Gram-negative bacterial infections. To understand the mechanisms underlying intrinsic polymyxin resistance in , we screened the Nebraska Transposon Mutant Library established in strain JE2 for increased susceptibility to polymyxin B. Nineteen mutants displayed at least 2-fold reductions in MIC, while the greatest reductions (8-fold) were observed for mutants with inactivation of either , , , or or the subunits of the ATP synthase (, , , or ), which during respiration is the main source of energy. Inactivation of also conferred hypersusceptibility to colistin and the aminoglycoside gentamicin, whereas susceptibilities to nisin, gallidermin, bacitracin, vancomycin, ciprofloxacin, linezolid, daptomycin, and oxacillin were unchanged. ATP synthase activity is known to be inhibited by oligomycin A, and the presence of this compound increased polymyxin B-mediated killing of Our results demonstrate that the ATP synthase contributes to intrinsic resistance of towards polymyxins and that inhibition of the ATP synthase sensitizes to this group of compounds. These findings show that by modulation of bacterial metabolism, new classes of antibiotics may show efficacy against pathogens towards which they were previously considered inapplicable. In light of the need for new treatment options for infections with serious pathogens like , this approach may pave the way for novel applications of existing antibiotics. Bacterial pathogens that cause disease in humans remain a serious threat to public health, and antibiotics are still our primary weapon in treating bacterial diseases. The ability to eradicate bacterial infections is critically challenged by development of resistance to all clinically available antibiotics. Polymyxins constitute an important class of antibiotics for treatment of infections caused by Gram-negative pathogens, whereas Gram-positive bacteria remain largely insusceptible towards class of antibiotics. Here we performed a whole-genome screen among nonessential genes for polymyxin intrinsic resistance determinants in We found that the ATP synthase is important for polymyxin susceptibility and that inhibition of the ATP synthase sensitizes towards polymyxins. Our study provides novel insights into the mechanisms that limit polymyxin activity against and provides valuable targets for inhibitors to potentially enable the use of polymyxins against and other Gram-positive pathogens.
固有地对多粘菌素（多粘菌素 B 和粘菌素）具有抗性，多粘菌素是一类用于治疗革兰氏阴性细菌感染的重要阳离子抗菌肽。为了了解内在多粘菌素抗性的机制，我们筛选了在 株 JE2 中建立的内布拉斯加转座子突变体库，以增加对多粘菌素 B 的敏感性。19 个突变体的 MIC 至少降低了 2 倍，而最大降低（8 倍）发生在失活 或 或 ATP 合酶的亚基（ ， ， 或 ）的突变体中，在呼吸过程中，ATP 合酶是能量的主要来源。 的失活也使粘菌素和氨基糖苷类庆大霉素的敏感性增加，而对尼生素、加力霉素、杆菌肽、万古霉素、环丙沙星、利奈唑胺、达托霉素和苯唑西林的敏感性不变。寡霉素 A 已知会抑制 ATP 合酶的活性，而这种化合物的存在增加了多粘菌素 B 对 的杀伤作用。我们的结果表明，ATP 合酶有助于 对多粘菌素的固有抗性，并且抑制 ATP 合酶使 对该类化合物敏感。这些发现表明，通过调节细菌代谢，新的抗生素类别可能对先前认为不适用的病原体具有疗效。鉴于需要新的治疗方案来治疗严重病原体如 引起的感染，这种方法可能为现有抗生素的新应用铺平道路。引起人类疾病的细菌病原体仍然对公共健康构成严重威胁，抗生素仍然是我们治疗细菌疾病的主要武器。由于所有临床可用抗生素都产生耐药性，因此消除细菌感染的能力受到严重挑战。多粘菌素是治疗革兰氏阴性病原体感染的一类重要抗生素，而革兰氏阳性细菌对该类抗生素的敏感性仍然很低。在这里，我们在内布拉斯加非必需基因中进行了全基因组筛选，以寻找 固有多粘菌素抗性决定因素。我们发现 ATP 合酶对多粘菌素的敏感性很重要，并且抑制 ATP 合酶使 对多粘菌素敏感。我们的研究为限制多粘菌素对 活性的机制提供了新的见解，并为抑制剂的潜在靶标提供了有价值的目标，以实现多粘菌素对 和其他革兰氏阳性病原体的使用。
