TY - JOUR T1 - A rapid method to determine the bactericidal activity of compounds against non-replicating <em>Mycobacterium tuberculosis</em> at low pH JF - bioRxiv DO - 10.1101/578195 SP - 578195 AU - Julie V. Early AU - Steven Mullen AU - Tanya Parish Y1 - 2019/01/01 UR - http://biorxiv.org/content/early/2019/03/14/578195.abstract N2 - There is an urgent need for new anti-tubercular agents which can lead to a shortened treatment time by targeting persistent or non-replicating bacilli. In order to assess compound activity against non-replicating Mycobacterium tuberculosis, we developed a method to detect the bactericidal activity of novel compounds within 7 days. Our method uses incubation at low pH in order to induce a non-replicating state. We used a strain of M. tuberculosis expressing luciferase; we first confirmed the linear relationship between luminescence and viable bacteria (determined by colony forming units) under our assay conditions. We optimized the assay parameters in 96-well plates in order to achieve a reproducible assay. Our final assay used M. tuberculosis in phosphate-citrate buffer, pH 4.5 exposed to compounds for 7 days; viable bacteria were determined by luminescence. We recorded the minimum bactericidal concentration at pH 4.5 (MBC4.5) representing &gt;2 logs of kill. We confirmed the utility of the assay with control compounds. The ionophores monensin, niclosamide, and carbonyl cyanide 3-chlorophenylhydrazone and the anit-tubercular drugs pretomanid and rifampicin were active, while several other drugs such as isoniazid, ethambutol, and linezolid were not. ER -