A method to survey heat labile anti-tuberculosis drugs

Introduction and objective: The appearance of resistance to anti-tuberculosis drugs has generated research to find new and more effective drugs. L wenstein-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.