Development of a microdilution method to evaluate Mycobacterium tuberculosis drug susceptibility

J Antimicrob Chemother. 2003 Nov;52(5):796-800. doi: 10.1093/jac/dkg439. Epub 2003 Sep 30.


A new rapid microdilution method, employing the dye resazurin as an indicator of mycobacterial growth, was developed to evaluate drug susceptibility of Mycobacterium tuberculosis reference strain H37Rv and of 13 M. tuberculosis susceptible or multidrug-resistant clinical strains. Different growth conditions were evaluated. The MICs of isoniazid, rifampicin, streptomycin and ethambutol were determined by the Microdilution Resazurin Assay (MRA) and the results compared with those obtained by the agar proportion method; complete agreement was always obtained. MRA resulted in a rapid, reliable, simple and inexpensive coloured method suitable for testing the susceptibility of M. tuberculosis clinical strains to first-line drugs; its employment in evaluating new antibacterial molecules is also suggested.

Publication types

  • Evaluation Study
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Agar
  • Antitubercular Agents / pharmacology*
  • Colony Count, Microbial
  • Culture Media
  • Humans
  • Indicators and Reagents / metabolism*
  • Microbial Sensitivity Tests / methods
  • Mycobacterium tuberculosis / drug effects*
  • Mycobacterium tuberculosis / growth & development*
  • Oxazines / metabolism*
  • Tuberculosis, Pulmonary / microbiology
  • Xanthenes*


  • Antitubercular Agents
  • Culture Media
  • Indicators and Reagents
  • Oxazines
  • Xanthenes
  • resazurin
  • Agar