Abstract

Introduction and objective: The appearance of resistance to anti-tuberculosis drugs has generated research to find new and more effective drugs. Lowenstein-Jensen medium (LJ) is frequently used for culturing strains of Mycobacterium tuberculosis. A group of antimicrobial substances used in treating tuberculosis is sensitive to heat and cannot be used on LJ medium. Research now aims to setup a modified method for evaluation of heat labile drugs in LS medium. Materials and methods: In this study, we investigated culturing M. tuberculosis for 48h on Middlebrook 7H9 broth medium with antituberculosis drugs and re culturing on LJ medium (without antibiotic) and incubating for 40 days. Results: Our results after 48h of contact of the strains with antibiotic were comparable with the standard method of culture on Middlebrook 7H10 agar medium containing antibiotic. Therefore, 48h is a suitable time for primary contact between mycobacterium and heat labile antibiotics. Conclusion: This modified method can be applied to LJ medium instead of expensive Middlebrook 7H10 agar medium for evaluation of heat labile anti tuberculosis drugs.