Anti-hepatitis C virus drug simeprevir: a promising antimicrobial agent against MRSA

Lusutrombopag as a Repurposing Drug in Combination with Aminoglycosides against Vancomycin-Resistant Enterococcus

Due to the widespread abuse of antibiotics, drug resistance in Enterococcus has been increasing. However, the speed of antibiotic discovery cannot keep pace with the acquisition of bacterial resistance. Thus, drug repurposing is a proposed strategy to solve the crises. Lusutrombopag (LP) has been approved as a thrombopoietin receptor agonist by the Food and Drug Administration. This study demonstrated that LP exhibited significant antimicrobial activities against vancomycin-resistant Enterococcus in vitro with rare resistance occurrence. Further, LP combined with tobramycin exhibited synergistic antimicrobial effects in vitro and in vivo against Enterococcus. No in vitro or in vivo detectable toxicity was observed when using LP. Mechanism studies indicated that the disrupted proton motive force may account for LP's antimicrobial activity. In summary, these results demonstrate that LP has the previously undocumented potential to serve as an antibacterial agent against refractory infections caused by Enterococcus.

Repurposing of the antimalarial agent tafenoquine to combat MRSA

IMPORTANCE

This study represents the first investigation into the antimicrobial effect of TAF against S. aureus and its potential mechanisms. Our data highlighted the effects of TAF against MRSA planktonic cells, biofilms, and persister cells, which is conducive to broadening the application of TAF. Through mechanistic studies, we revealed that TAF targets bacterial cell membranes. In addition, the in vivo experiments in mice demonstrated the safety and antimicrobial efficacy of TAF, suggesting that TAF could be a potential antibacterial drug candidate for the treatment of infections caused by multiple drug-resistant S. aureus.

Simeprevir restores the anti-Staphylococcus activity of polymyxins

Methicillin-resistant Staphylococcus aureus (MRSA) infection poses a severe threat to global public health due to its high mortality. Currently, polymyxins are mainly used for the treatment of Gram-negative bacterial-related infection, while exhibiting limited antibacterial activities against Staphylococcus aureus (S. aureus). However, the combination of antibiotics with antibiotic adjuvants is a feasible strategy for the hard-treated infection and toxicity reducing. We will investigate the antibacterial activity of simeprevir (SIM), which treated for genotype 1 and 4 chronic hepatitis C, combined with polymyxins against MRSA through high-throughput screening technology. In our study, the synergistic antibacterial effect of SIM and polymyxins against S. aureus in vitro was found by checkerboard assay and time-growth curve. The cytotoxicity of SIM combined with polymyxin B sulfate [PB(S)] or polymyxin E (PE) in vitro was evaluated using CCK-8, human RBC hemolysis and scratch assays. In addition, we investigated the eradication of biofilm formation of S. aureus by biofilm inhibition assay and the killing of persister cells. Moreover, we evaluated the therapeutic effect and in vivo toxicity of the combination against MRSA in murine subcutaneous abscess model. Furthermore, it was preliminarily found that SIM significantly enhanced the destruction of MRSA membrane by SYTOX Green and DISC3(5) probes. In summary, these results reveal that the therapy of SIM combined with polymyxins (especially PE) is promising for the treatment of MRSA infection.

Repurposing CD5789 as an Antimicrobial Agent Against MRSA and Its High Resistant Phonotypes

Methicillin-resistant Staphylococcus aureus (MRSA) poses a great threat to human health, and the formation of biofilm and persister cells make the situation even worse. Drug repurposing is an effective way to solve this problem by shortening the drug development times and reducing the research costs. In this study, CD5789 (trifarotene), a fourth-generation retinoid to be approved by the FDA in 2019 for the topical acne vulgaris regimens, was exhibited antimicrobial activity against MRSA type strains and its clinical isolates with the minimal concentration (MIC) of 2-4 μg/mL and 4-16 μg/mL, respectively, in a dose-dependent manner. By crystal violet staining, we found that CD5789 could inhibit the biofilm formation by MRSA and could further eradicate the pre-formed biofilm at the concentration of 8 μg/mL. By checkerboard dilution assay, sub-MIC of CD5789 showed synergistic antimicrobial effects with sub-MIC of gentamycin against MRSA type strains as well as clinical isolates. In addition, CD5789 also exhibited effective bactericidal activity against MRSA persister cells at the concentration of 8 ~ 16 μg/mL. Extremely low cytotoxicity of CD5789 was observed by CCK-8 assay indicated the well tolerability to human body. In all, CD5789 has the potential to be an alternative for the treatment of refractory MRSA-related infections.