UT-ORNL Graduate School of Genome Science and Technology, University of Tennessee, Knoxville, TN, United States of America.
Department of Chemistry, University of Tennessee, Knoxville, TN, United States of America.
PLoS One. 2021 Jul 23;16(7):e0254796. doi: 10.1371/journal.pone.0254796. eCollection 2021.
Daptomycin is a cyclic lipopeptide antibiotic used in the clinic for treatment of severe enterococcal infections. Recent reports indicate that daptomycin targets active cellular processes, specifically, peptidoglycan biosynthesis. Within, we examined the efficacy of daptomycin against Enterococcus faecalis under a range of environmental growth conditions including inhibitors that target active cellular processes. Daptomycin was far less effective against cells in late stationary phase compared to cells in exponential phase, and this was independent of cellular ATP levels. Further, the addition of either the de novo protein synthesis inhibitor chloramphenicol or the fatty acid biosynthesis inhibitor cerulenin induced survival against daptomycin far better than controls. Alterations in metabolites associated with peptidoglycan synthesis correlated with protection against daptomycin. This was further supported as removal of peptidoglycan induced physiological daptomycin tolerance, a synergistic relation between daptomycin and fosfomycin, an inhibitor of the fist committed step peptidoglycan synthesis, was observed, as well as an additive effect when daptomycin was combined with ampicillin, which targets crosslinking of peptidoglycan strands. Removal of the peptidoglycan of Enterococcus faecium, Staphylococcus aureus, and Bacillus subtilis also resulted in significant protection against daptomycin in comparison to whole cells with intact cell walls. Based on these observations, we conclude that bacterial growth phase and metabolic activity, as well as the presence/absence of peptidoglycan are major contributors to the efficacy of daptomycin.
达托霉素是一种临床上用于治疗严重肠球菌感染的环状脂肽抗生素。最近的报告表明，达托霉素针对的是活跃的细胞过程，特别是肽聚糖生物合成。在本研究中，我们考察了达托霉素在包括靶向活跃细胞过程抑制剂在内的一系列环境生长条件下对粪肠球菌的疗效。与指数生长期的细胞相比，晚期稳定期的细胞对达托霉素的敏感性要低得多，这与细胞内 ATP 水平无关。此外，添加新的蛋白质合成抑制剂氯霉素或脂肪酸生物合成抑制剂杆菌肽，可诱导对达托霉素的生存能力比对照药物好得多。与肽聚糖合成相关的代谢物的变化与对达托霉素的保护作用相关。这进一步得到了支持，因为去除肽聚糖诱导了生理性的达托霉素耐受，达托霉素与抑制肽聚糖合成第一步的磷霉素之间存在协同关系，并且当达托霉素与氨苄西林联合使用时，也存在相加效应，氨苄西林可靶向肽聚糖链的交联。与完整细胞壁的细胞相比，去除粪肠球菌、金黄色葡萄球菌和枯草芽孢杆菌的肽聚糖也会导致对达托霉素的显著保护作用。基于这些观察结果，我们得出结论，细菌的生长阶段和代谢活性，以及肽聚糖的存在与否，是达托霉素疗效的主要影响因素。
