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Staphylococcus aureusis responsible for a substantial number of invasive infections globally each year. These infections are problematic because they are frequently recalcitrant to antibiotic treatment, particularly when they are caused by Methicillin-ResistantStaphylococcus aureus(MRSA). Antibiotic tolerance, the ability for bacteria to persist despite normally lethal doses of antibiotics, is responsible for most antibiotic treatment failure in MRSA infections. To understand how antibiotic tolerance is induced,S. aureusbiofilms exposed to multiple anti-MRSA antibiotics (vancomycin, ceftaroline, delafloxacin, and linezolid) were examined using both quantitative proteomics and transposon sequencing. These screens indicated that arginine metabolism is involved in antibiotic tolerance within a biofilm and led to the hypothesis that depletion of arginine withinS. aureuscommunities can induce antibiotic tolerance. Consistent with this hypothesis, inactivation ofargH,the final gene in the arginine synthesis pathway, induces antibiotic tolerance under conditions in which the parental strain is susceptible to antibiotics. Arginine restriction was found to induce antibiotic tolerance via inhibition of protein synthesis. Finally, althoughS. aureusfitness in a mouse skin infection model is decreased in anargHmutant, its ability to survivein vivoduring antibiotic treatment with vancomycin is enhanced, highlighting the relationship between arginine metabolism and antibiotic tolerance duringS. aureusinfection. Uncovering this link between arginine metabolism and antibiotic tolerance has the potential to open new therapeutic avenues targeting previously recalcitrantS. aureusinfections.

Significance Statement

Methicillin-ResistantStaphylococcus aureus(MRSA) is a leading bacterial cause of morbidity and mortality worldwide. Despite the availability of numerous antibiotics within vitroefficacy against MRSA, there are still high rates of antibiotic treatment failure inS. aureusinfections, suggesting antibiotic tolerance is common during human infections. Here, we report a direct connection between the metabolism of arginine, an essential amino acid inS. aureus, and tolerance to multiple classes of antibiotics. This represents a key pathway towards broad antibiotic tolerance inS. aureusand therefore an attractive target to help repotentiate current antibiotics and potentially reduce treatment failure.