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Antibiotic lethality is a complex physiological process, sensitive to external cues. Recent advances using systems approaches have revealed how events downstream of primary target inhibition actively participate in antibiotic death processes. In particular, altered metabolism, translational stress and DNA damage each contribute to antibiotic-induced cell death. Moreover, environmental factors such as oxygen availability, extracellular metabolites, population heterogeneity and multidrug contexts alter antibiotic efficacy by impacting bacterial metabolism and stress responses. Here we review recent studies on antibiotic efficacy and highlight insights gained on the involvement of cellular respiration, redox stress and altered metabolism in antibiotic lethality. We discuss the complexity found in natural environments and highlight knowledge gaps in antibiotic lethality that may be addressed using systems approaches., National Institutes of Health (U.S.) (Grant K99GM118907), National Institutes of Health (U.S.) (Grant U19AI111276), National Science Foundation (U.S.) (Award 1122374), Defense Threat Reduction Agency (DTRA) (Award HDTRA1-15-1-0051)

Metabolically dormant bacteria present a critical challenge to effective antimicrobial therapy because these bacteria are genetically susceptible to antibiotic treatment but phenotypically tolerant. Such tolerance has been attributed to impaired drug uptake, which can be reversed by metabolic stimulation. Here, we evaluate the effects of central carbon metabolite stimulations on aminoglycoside sensitivity in the pathogen Pseudomonas aeruginosa. We identify fumarate as a tobramycin potentiator that activates cellular respiration and generates a proton motive force by stimulating the tricarboxylic acid (TCA) cycle. In contrast, we find that glyoxylate induces phenotypic tolerance by inhibiting cellular respiration with acetyl-coenzyme A diversion through the glyoxylate shunt, despite drug import. Collectively, this work demonstrates that TCA cycle activity is important for both aminoglycoside uptake and downstream lethality and identifies a potential strategy for potentiating aminoglycoside treatment of P. aeruginosa infections. Keyword: aminoglycoside susceptibility; Pseudomonas aeruginosa; TCA cycle; respiration; electron transport chain; fumarate; glyoxylate; biochemical persistence; LC-MS metabolomics, Defense Threat Reduction Agency (DTRA) (Grant HDTRA1-15-1-0051), National Institutes of Health (U.S.) (Grant NIH K99GM118907)

Bactericidal antibiotics alter microbial metabolism as part of their lethality and can damage mitochondria in mammalian cells. In addition, antibiotic susceptibility is sensitive to extracellular metabolites, but it remains unknown whether metabolites present at an infection site can affect either treatment efficacy or immune function. Here, we quantify local metabolic changes in the host microenvironment following antibiotic treatment for a peritoneal Escherichia coli infection. Antibiotic treatment elicits microbiome-independent changes in local metabolites, but not those distal to the infection site, by acting directly on host cells. The metabolites induced during treatment, such as AMP, reduce antibiotic efficacy and enhance phagocytic killing. Moreover, antibiotic treatment impairs immune function by inhibiting respiratory activity in immune cells. Collectively, these results highlight the immunomodulatory potential of antibiotics and reveal the local metabolic microenvironment to be an important determinant of infection resolution. Antibiotic susceptibility is sensitive to metabolites, but how this affects in vivo treatment efficacy remains unexplored. Yang, Bhargava et al. characterize antibiotic-induced changes to the metabolic environment during infection and find that direct actions of antibiotics on host cells induce metabolites that impair drug efficacy and enhance phagocytic activity., United States. Defense Threat Reduction Agency (Grant HDTRA1-15-1-0051), National Institutes of Health (U.S.) (Grant U01AI124316), National Institutes of Health (U.S.) (Grant K99GM118907), Novo Nordisk Foundation (Grant NNF16CC0021858), Paul G. Allen Frontiers Group, Wyss Institute for Biologically Inspired Engineering