Drug-Resistant TB

• Most strains of the TB bacteria require at least two drugs to prevent resistance.



• Resistance is caused by inconsistent or partial treatment. In some instances, patients are prescribed inadequate therapy or enough drug is not available. Usually this occurs because patients tend to stop taking their medication once they start to feel better. Observed therapy is often required and monitored by health departments in the U.S.



• Multidrug-resistant TB (MDR-TB) is caused by a bacteria that is resistant to at least isoniazid and rifampicin. Prolonged alternative therapy is required to treat this form of TB, often for up to two years.



• Extensively drug-resistant TB (XDR-TB) is rare but extremely problematic. This form of TB is very difficult to treat and often requires prolonged isolation of the individual to protect the community at large. If TB is treated properly and consistently, these resistant forms are much less likely to spread.