Rose Warren E, Ersoy Selvi C, Abdelhady Wessam, Dominguez Alan R, Muyah Manna Jedidiah Ndam, Artaza Jorge N, Mishra Reetakshi, Elsayed Ahmed M, Proctor Richard A, Baines Sarah L, Howden Benjamin P, Mishra Nagendra N
School of Pharmacy, University of Wisconsin-Madison, Madison, WI 53705, USA.
Division of Infectious Diseases, The Lundquist Institute at Harbor-UCLA Medical Center, Torrance, CA 90502, USA.
Microorganisms. 2025 Jun 30;13(7):1532. doi: 10.3390/microorganisms13071532.
This study elucidates potential genetic determinants and mechanisms involved in the synergistic effects of daptomycin (DAP) + fosfomycin (FOF) combination therapy. Among 33 clinically derived DAP-susceptible (S)/DAP-resistant (R) isogenic strain pairs, mutations in the gene occurred in 30/33 DAP-R strains, including polymorphisms of L826F (33%) or T345A/L/I (15%). Strain variants of DAP-S CB1483 serially passaged in vitro for 10 days in DAP +/- FOF identified a key non-synonymous mutation in (L826F) only in the DAP monotherapy arm. Interestingly, passage in FOF alone or DAP + FOF prevented the emergence of this mutation following 10-day passage. This L826F mprF polymorphism, associated with a "gain-in-function" phenotype, exhibited increased amounts of lysyl-phosphatidylglycerol (L-PG) in the cell membrane (CM). Transcriptomics revealed a relatively modest number (~10) of distinct genes that were significantly up- or downregulated (≥2 log fold) in both the DAP-S and DAP-R strain pairs upon DAP + FOF exposures (vs. DAP or FOF alone). Of note, DAP + FOF decreased expression of and and increased the expression level of . In a rabbit infective endocarditis (IE) model, the DAP-R CB185 strain treated with DAP +/- FOF showed significantly reduced expression in vegetations compared with DAP treatment alone. Overall, these findings indicate that DAP + FOF therapy impacts MRSA through multiple specific mechanisms, enhancing bacterial clearance.
本研究阐明了达托霉素（DAP）+磷霉素（FOF）联合治疗协同效应中潜在的遗传决定因素和机制。在33对临床分离的对DAP敏感（S）/耐药（R）的同基因菌株中，30/33株DAP-R菌株发生了基因中的突变，包括L826F（33%）或T345A/L/I（15%）的多态性。DAP-S CB1483菌株变体在含有DAP +/- FOF的培养基中体外连续传代10天，结果仅在DAP单药治疗组中发现了（L826F）中的一个关键非同义突变。有趣的是，单独在FOF中传代或在DAP + FOF中传代可防止该突变在传代10天后出现。这种与“功能获得”表型相关的L826F mprF多态性在细胞膜（CM）中表现出赖氨酰磷脂酰甘油（L-PG）含量增加。转录组学显示，在DAP + FOF暴露后（与单独使用DAP或FOF相比），DAP-S和DAP-R菌株对中显著上调或下调（≥2倍对数）的不同基因数量相对较少（约10个）。值得注意的是，DAP + FOF降低了和的表达，并增加了的表达水平。在兔感染性心内膜炎（IE）模型中，与单独使用DAP治疗相比，用DAP +/- FOF治疗的DAP-R CB185菌株在赘生物中的表达显著降低。总体而言，这些发现表明DAP + FOF治疗通过多种特定机制影响耐甲氧西林金黄色葡萄球菌（MRSA），增强细菌清除。
