A comparison of conventional and radiometric methods for the assessment of anti-tubercular activity of drugs against Mycobacterium tuberculosis in mice and macrophage models.

Background: Presently, in vitro and in vivo screening of anti-tubercular drugs is a time-consuming exercise. Therefore, it is important to develop faster methods.
Material and Methods: Towards this end, conventional plating and radiometric BACTEC methods of anti-tubercular screening were compared to determine the efficacy of anti-tubercular drugs (isoniazid and rifampicin) and morphine in Mycobacterium tuberculosis H37Rv-infected mice and macrophages.
Results: A linear correlation (R2 = 0.95) was observed between number of colony forming units (CFUs) and growth index (GI) values. BACTEC method was found to be faster and sensitive as compared to plating method. Further, BACTEC method, being a closed system, appeared to be less susceptible to microbial contamination and poses less biohazard.
Conclusion: We conclude that BACTEC method can be employed for easy, precise, and rapid screening of anti-tubercular compounds and morphine in mice and macrophage models.