sentences:  Globally, most MDR-TB cases occur in South America, Southern Africa, India, China, and the former Soviet Union.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.Under ideal program conditions, MDR-TB cure rates can approach 70%.