Repurposing of the antimalarial agent tafenoquine to combat MRSA

Abstract

ABSTRACT Staphylococcus aureus is an important human pathogen that often leads to hospital-acquired and community-acquired infections. The appearance of methicillin-resistant S. aureus (MRSA) has made the treatment extremely challenging. There is an urgent need to develop new antimicrobial agents to combat MRSA infections. In this study, through high-throughput screening, we found that tafenoquine (TAF), an antimalarial agent, exhibited antimicrobial efficacy against MRSA and its highly resistant phenotypes of biofilm and persister cells. No resistant mutation emerged by consecutive sub-minimal inhibitory concentration of TAF induction. Mechanistic studies by fluorescent probes of SYTOX Green/DiSC3(5), molecular dynamic simulations, electron microscopy, and proteomic analysis revealed that TAF exerts antimicrobial activity mainly through selective bacterial cell membrane disruption. In addition, TAF exhibited an effective antimicrobial effect in a subcutaneous abscess model in vivo with a good toxicity profile. In conclusion, TAF may have the potential to be developed as a new antimicrobial agent to treat refractory MRSA infections. 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 .