n -Butanol Potentiates Subinhibitory Aminoglycosides against Bacterial Persisters and Multidrug-Resistant MRSA by Rapidly Enhancing Antibiotic Uptake.

Potentiation of traditional antibiotics is of significance for combating antibiotic-resistant bacteria that have become a severe threat to human and animal health. Here, we report that 1 min co-treatment with n -butanol greatly and specifically enhances the bactericidal action of aminoglycosides by 5 orders of magnitude against stationary-phase Staphylococcus aureus cells, with n -propanol and isobutanol showing less potency. This combined treatment also rapidly kills various S. aureus persisters, methicillin-resistant S. aureus (MRSA) cells, and numerous Gram-positive and -negative pathogens including some clinically isolated multidrug-resistant pathogens ( e.g. , S. aureus , Staphylococcus epidermidis , and Enterococcus faecalis ) in vitro , as well as S. aureus in mice. Mechanistically, the potentiation results from the actions of aminoglycosides on their conventional target ribosome rather than the antiseptic effect of n -butanol and is achieved by rapidly enhancing the bacterial uptake of aminoglycosides, while salts and inhibitors of proton motive force ( e.g. , CCCP) can diminish this uptake. Importantly, such n -butanol-enhanced antibiotic uptake even enables subinhibitory concentrations of aminoglycosides to rapidly kill both MRSA and conventional S. aureus cells. Given n -butanol is a non-metabolite in the pathogens we tested, our work may open avenues to develop a metabolite-independent strategy for aminoglycoside potentiation to rapidly eliminate antibiotic-resistant/tolerant pathogens, as well as for reducing the toxicity associated with aminoglycoside use.