Alarmed by the emergence of strains of extremely drug-resistant tuberculosis (TB), global health experts are calling for stepped-up efforts to prevent a future epidemic of virtually untreatable TB. The extensively drug-resistant TB strains, called XDR TB, are resistant to the 2 main first-line TB drugs, isoniazid and rifampicin, as well as to 3 or more of the 6 classes of second-line drugs (MMWR Morb Mortal Wkly Rep. 2006;55:301-305).
Stephenson J. Extreme TB Threat. JAMA. 2006;296(15):1830. doi:10.1001/jama.296.15.1830-b