More than 70 years ago, Hobby 1 and Bigger 2 observed that antibiotics that are considered bactericidal and kill bacteria in fact fail to sterilize cultures. Bigger realized that the small number of bacteria that manage to survive intensive antibiotic treatments are a distinct subpopulation of bacteria that he named 'persisters'. Fuelled in part by increasing concerns about antibiotic resistance but also by technological advances in single-cell analyses, the past 15 years have witnessed a great deal of research on antibiotic persistence by investigators with different backgrounds and perspectives. As the number of scientists that tackle the puzzles and challenges of antibiotic persistence from many different angles has profoundly increased, it is now time to agree on the basic definition of persistence and its distinction from the other mechanisms by which bacteria survive exposure to bactericidal antibiotic treatments 3. Several approaches have independently emerged to define and measure persistence. Research groups following seemingly similar procedures may reach different results, and careful examination of the experimental procedures often reveals that results of different groups cannot be compared. During the European Molecular Biology Organization (EMBO) Workshop 'Bacterial Persistence and Antimicrobial Therapy' (10-14 June 2018) in Ascona, Switzerland, which brought together 121 investigators involved in antibiotic persistence research from 21 countries, a discussion panel laid the main themes for a Consensus Statement on the definition and detection procedure of antibiotic persistence detailed below. In light of the potential role that antibiotic persistence can have in antibiotic treatment regimens, it is our hope that clarification and standardization of experimental procedures will facilitate the translation of basic science research into practical guidelines. Defining the persistence phenomena We adopt here a phenomenological definition of antibiotic persistence that is based on a small set of observations that can be made from experiments performed in vitro and that does not assume a specific mechanism. We focus on the differences and similarities between antibiotic persistence and other processes enabling bacteria to survive exposure to antibiotic treatments that could kill them, such as resistance, tolerance and heteroresistance. We identify different types of persistence that should be measured differently to obtain meaningful results; therefore, the definition of these types goes beyond semantics. For the more mathematically oriented readers, we provide a mathematical definition of the

Bacterial persistence is a state in which a sub-population of dormant cells (persisters) tolerates antibiotic treatment1-4. Bacterial persisters have been implicated in biofilms and chronic and recurrent infections5-7. Despite this clinical relevance, there are currently no viable means for eradicating persisters. Here we show that specific metabolic stimuli enable aminoglycoside killing of both Gram-negative (Escherichia coli) and Gram-positive (Staphylococcus aureus) persisters. This potentiation is aminoglycoside-specific, does not rely on growth resumption, is effective in both aerobic and anaerobic conditions, and proceeds by generation of proton-motive force (PMF) which facilitates aminoglycoside uptake. Our results demonstrate that persisters, though dormant, are primed for metabolite uptake, central metabolism, and respiration. We show that aminoglycosides in combination with specific metabolites can be used to treat E. coli and S. aureus biofilms. Further, we demonstrate that this approach can improve treatment of chronic infection in a mouse urinary tract infection model. This work establishes a metabolic-based strategy for eradicating bacterial persisters and highlights the critical importance of metabolic environment to antibiotic treatment.

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