Abstract: Tuberculosis remains a threat to global pandemic, it becomes more difficult to control TB due to the emergence of multidrug-resistant and extensively drug-resistant Mycobacterium tuberculosis. Preventing the resistance to a paticular drug, WHO has recommended the combined modality therapy with several drugs as the main method in the treatment of TB. Individualized treatment plan, based on the drug susceptibility results, should be taken in the treatment of drug-resistant TB. So far, the drug susceptibility test is mostly carried out for monotherapy. However, in some cases, even the single drug susceptibility results are resistant, the combined modality therapy still performances better therapeutic effect, which reminds us that the combination of several drugs used in treatment may enhance its antibacterial activity. At present, because of the severe drug resistance of first-line drugs and the shortcoming of second-line drugs (such as price，toxicity and so on), we urgently need to find a new anti-TB chemotherapy to control the prevalence of drug-resistant. Before creating a new chemistry program, it is important to conduct quantified experiments repeatedly to evaluate the antimicrobial activity of the combined modality therapy.

Key words: Mycobacterium tuberculosis, Microbial sensitivity tests