Brevicidine, a bacterial non-ribosomally produced cyclic antimicrobial lipopeptide with a unique modus operandi

Due to the accelerated appearance of antibiotic-resistant (AMR) pathogens in clinical infections, new first-in-class antibiotics, operating via novel modes of action, are desperately-needed. Brevicidine, a bacterial non-ribosomally produced cyclic lipopeptide, has shown potent and selective antimicrobial activity against Gram-negative pathogens. However, before our investigations, little was known about how brevicidine exerts its potent bactericidal effect against Gram-negative pathogens. In this study, we find that brevicidine has potent antimicrobial activity against AMR Enterobacteriaceae pathogens, with a MIC value ranging between 0.5M (0.8mg/L) and 2M (3.0mg/L). In addition, brevicidine showed potent anti-biofilm activity against the Enterobacteriaceae pathogens, with same 100% inhibition and 100% eradication concentration of 4M (6.1mg/L). Further mechanistic studies showed that brevicidine exerts its potent bactericidal activity via interacting with lipopolysaccharide in the outer membrane, targeting phosphatidylglycerol and cardiolipin in the inner membrane, and dissipating the proton motive force of bacteria. This results in metabolic perturbation, including inhibition of adenosine triphosphate synthesis, inhibits the dehydrogenation of nicotinamide adenine dinucleotides, accumulation of reactive oxygen species in bacteria, and inhibition of protein synthesis. Lastly, brevicidine showed a good therapeutic effect in a mouse peritonitis-sepsis model. Our findings pave the way for further research on clinical applications of brevicidine, to combat the prevalent infections caused by AMR Gram-negative pathogens worldwide.