Tuberculosis and Mycobacteria

Resistance to TB drugs

Primary MDR-TB occurs in patients who have not previously been infected with TB but who become infected with a strain that is resistant to treatment. Acquired MDR-TB occurs in patients during treatment with a drug regimen that is not effective at killing the particular strain of TB with which they have been infected Treatment of MDR-TB requires treatment with second-line drugs, usually four or more anti-TB drugs for a minimum of 6 months, and possibly extending for 18–24 months if rifampin resistance has been identified in the specific strain of TB with which the patient has been infected.In general, second-line drugs are less effective, more toxic and much more expensive than first-line drugs. Under ideal program conditions, MDR-TB cure rates can approach 70%.