title: Low-oxygen-recovery assay for high-throughput screening of compounds against nonreplicating Mycobacterium tuberculosis.
abstract: Screening for new antimicrobial agents is routinely conducted only against actively replicating bacteria. However, it is now widely accepted that a physiological state of nonreplicating persistence (NRP) is responsible for antimicrobial tolerance in many bacterial infections. In tuberculosis, the key to shortening the 6-month regimen lies in targeting this NRP subpopulation. Therefore, a high-throughput, luminescence-based low-oxygen-recovery assay (LORA) was developed to screen antimicrobial agents against NRP Mycobacterium tuberculosis. M. tuberculosis H37Rv containing a plasmid with an acetamidase promoter driving a bacterial luciferase gene was adapted to low oxygen conditions by extended culture in a fermentor with a 0.5 headspace ratio. The MICs of 31 established antimicrobial agents were determined in microplate cultures maintained under anaerobic conditions for 10 days and, for comparative purposes, under aerobic conditions for 7 days. Cultures exposed to drugs under anaerobic conditions followed by 28 h of "recovery" under ambient oxygen produced a luminescent signal that was, for most compounds, proportional to the number of CFU determined prior to the recovery phase. No agents targeting the cell wall were active against NRP M. tuberculosis, whereas drugs hitting other cellular targets had a range of activities. The calculated Z' factor was in the range of 0.58 to 0.84, indicating the suitability of the use of LORA for high-throughput assays. This LORA is sufficiently robust for use for primary high-throughput screening of compounds against NRP M. tuberculosis.
authors.affiliation: Institute for Tuberculosis Research, Department of Medicinal Chemistry and Pharmacognosy, College of Pharmacy, University of Illinois at Chicago, 833 South Wood Street, MC 964, Rm. 412, Chicago, IL 60612, USA.
authors.forename: Sang Hyun
authors.initials: SH
authors.lastname: Cho
authors.forename: Saradee
authors.initials: S
authors.lastname: Warit
authors.forename: Baojie
authors.initials: B
authors.lastname: Wan
authors.forename: Chang Hwa
authors.initials: CH
authors.lastname: Hwang
authors.forename: Guido F
authors.initials: GF
authors.lastname: Pauli
authors.forename: Scott G
authors.initials: SG
authors.lastname: Franzblau
mesh_terms: D000900:Anti-Bacterial Agents / Q000494:pharmacology*; D000995:Antitubercular Agents / Q000494:pharmacology*; D004269:DNA, Bacterial / Q000096:biosynthesis; D004353:Drug Evaluation, Preclinical / Q000379:methods*; D009169:Mycobacterium tuberculosis / Q000187:drug effects* / Q000254:growth & development*; D010100:Oxygen / Q000378:metabolism*
chemical_list: D000900:Anti-Bacterial Agents; D000995:Antitubercular Agents; D004269:DNA, Bacterial; D010100:Oxygen