MDR-TB is a growing threat to international health. A recent report from WHO estimated that over 440,000 new cases of MDR-TB occurred in 127 countries in 2008, causing 150,000 deaths; this represents a 55% increase in the number of cases since 2000. Current treatment regimens have only a 58-67% success rate, and as many as 20% of those who fail to respond to treatment die of tuberculosis; those who do not die become chronic carriers and spread MDR-TB to others.