Heat shock potentiates aminoglycosides against gram-negative bacteria by enhancing antibiotic uptake, protein aggregation, and ROS.

Abstract

The potentiation of antibiotics is a promising strategy for combatting antibiotic-resistant/tolerant bacteria. Herein, we report that a 5-min sublethal heat shock enhances the bactericidal actions of aminoglycoside antibiotics by six orders of magnitude against both exponential- and stationary-phase <i>Escherichia coli</i>. This combined treatment also effectively kills various <i>E. coli</i> persisters, <i>E. coli</i> clinical isolates, and numerous gram-negative but not gram-positive bacteria and enables aminoglycosides at 5% of minimum inhibitory concentrations to eradicate multidrug-resistant pathogens <i>Acinetobacter baumannii</i> and <i>Klebsiella pneumoniae</i>. Mechanistically, the potentiation is achieved comprehensively by heat shock-enhanced proton motive force that thus promotes the bacterial uptake of aminoglycosides, as well as by increasing irreversible protein aggregation and reactive oxygen species that further augment the downstream lethality of aminoglycosides. Consistently, protonophores, chemical chaperones, antioxidants, and anaerobic culturing abolish heat shock-enhanced aminoglycoside lethality. We also demonstrate as a proof of concept that infrared irradiation- or photothermal nanosphere-induced thermal treatments potentiate aminoglycoside killing of <i>Pseudomonas aeruginosa</i> in a mouse acute skin wound model. Our study advances the understanding of the mechanism of actions of aminoglycosides and demonstrates a high potential for thermal ablation in curing bacterial infections when combined with aminoglycosides.