Membrane Phenotypic, Metabolic and Genotypic Adaptations of Strains Destined to Rapidly Develop Stable, High-Level Daptomycin Resistance during Daptomycin Exposures.

The subgroup of viridans group streptococci are important human pathogens. We previously showed that a substantial portion of strains (>25%) are 'destined' to develop rapid, high-level, and stable daptomycin (DAP) resistance (DAP-R) during DAP exposures in vitro. Such DAP-R is often accompanied by perturbations in distinct membrane phenotypes and metabolic pathways.

Combinations of Daptomycin plus Ceftriaxone, but Not Ascending Daptomycin Dose-Regimens, Are Effective in Experimental Endocarditis Caused by Streptococcus mitis Strains: Target Tissue Clearances and Prevention of Emergence of Daptomycin-Resistance.

The Streptococcus mitis subgroup of the viridans group streptococci (VGS) are the most common cause of infective endocarditis (IE) in many parts of the world. These organisms are frequently resistant to standard β-lactams (e.g.

Activity of the Lactate Dehydrogenase Inhibitor Oxamic Acid against the Fermentative Bacterium : Bactericidal Effects and Prevention of Daptomycin Resistance In Vitro and in an Ex Vivo Model.

is a fermentative bacterium that relies on lactate dehydrogenase to balance its redox poise and keep glycolysis active. Metabolomic analysis of an in vitro-derived daptomycin-resistant (DAP-R) strain (351-D10) revealed differences in glucose catabolism relative to its DAP-susceptible (DAP-S) parental strain, 351. Metabolic changes associated with the transition to this DAP-R phenotype suggested that inhibiting glycolysis could alter DAP susceptibility.

Synergy Mechanisms of Daptomycin-Fosfomycin Combinations in Daptomycin-Susceptible and -Resistant Methicillin-Resistant Staphylococcus aureus: , , and Metrics.

Increased usage of daptomycin (DAP) for methicillin-resistant Staphylococcus aureus (MRSA) infections has led to emergence of DAP-resistant (DAP-R) strains, resulting in treatment failures. DAP-fosfomycin (Fosfo) combinations are synergistically active against MRSA, although the mechanism(s) of this interaction is not fully understood. The current study explored four unique but likely interrelated activities of DAP-Fosfo combinations: (i) synergistic killing, (ii) prevention of evolution of DAP-R, (iii) resensitization of already DAP-R subpopulations to a DAP-susceptible (DAP-S) phenotype, and (iv) perturbations of specific cell envelope phenotypes known to correlate with DAP-R in MRSA.

Cell Membrane Adaptations Mediate β-Lactam-Induced Resensitization of Daptomycin-Resistant (DAP-R) In Vitro.

The reversal of daptomycin resistance in MRSA to a daptomycin-susceptible phenotype following prolonged passage in selected β-lactams occurs coincident with the accumulation of multiple point mutations in the gene. MprF regulates surface charge by modulating the content and translocation of the positively charged cell membrane phospholipid, lysyl-phosphatidylglycerol (LPG). The precise cell membrane adaptations accompanying such β-lactam-induced perturbations are unknown.