Preventing the next generation of extensively drug-resistant tuberculosis.

Multidrug-resistant and extremely drug-resistant tuberculosis strains threaten to become an intractable problem. Misuse of antibiotics and inadequacy of diagnostic tools have fostered drug resistance. Effective diagnostic technology would eliminate this problem, but it remains unavailable in high-burden areas. New drugs with novel targets may help combat drug resistance. However, if added singly to existing combination regimens, resistance will increase. To protect the efficacy of a new drug, it should first be used only as a second-line drug, in cases that have undergone drug susceptibility testing. Widespread use of new drugs as first-line agents would follow with the dawn of a new rapid diagnostic era.