| Title | Detection of Inhibitors of Phenotypically Drug-tolerant Mycobacterium tuberculosis Using an In Vitro Bactericidal Screen |
|---|---|
| Author | Ian M. Bassett1, Shichun Lun2, William R. Bishai2, Haidan Guo2, Joanna R. Kirman3, Mudassar Altaf1, and Ronan F. O’Toole4* |
| Address | 1School of Biological Sciences, Victoria University of Wellington, New Zealand, 2Center for Tuberculosis Research, Johns Hopkins University, Baltimore, USA, 3Department of Microbiology and Immunology, University of Otago, Dunedin, New Zealand, 4Department of Clinical Microbiology, School of Medicine, Trinity College Dublin, Ireland |
| Bibliography | Journal of Microbiology, 51(5),651-658, 2013, |
| DOI | 10.1007/s12275-013-3099-4 |
| Key Words | Mycobacterium tuberculosis, phenotypic drug tolerance, chemical library screening |
| Abstract | Many whole cell screens of chemical libraries currently in use are based on inhibition of bacterial growth. The goal of this study was to develop a chemical library screening model that enabled detection of compounds that are active against drug-tolerant non-growing cultures of Mycobacterium tuberculosis. An in vitro model of low metabolically active mycobacteria was established with 8 and 30 day old cultures of M. smegmatis and M. tuberculosis, respectively. Reduction of resazurin was used as a measure of viability and the assay was applied in screens of chemical libraries for bactericidal compounds. The model provided cells that were phenotypically-resilient to killing by first and second-line clinical drugs including rifampicin. Screening against chemical libraries identified proteasome inhibitors, NSC310551 and NSC321206, and a structurally-related series of thiosemicarbazones, as having potent killing activity towards aged cultures. The inhibitors were confirmed as active against virulent M. tuberculosis strains including multi- and extensively-drug resistant clinical isolates. Our library screen enabled detection of compounds with a potent level of bactericidal activity towards phenotypically drug-tolerant cultures of M. tuberculosis. |