Rapid Drug Susceptibility Testing with a Molecular Beacon Assay Is

To assess the clinical impact of a molecular beacon (MB) assay that detects multidrug-resistant tuberculosis (MDR TB), we retrospectively reviewed records of 127 MDR TB patients with and without MB testing between 2004 and 2007. Use of the MB assay reduced the time to detection and treatment of MDR TB. The emergence and spread of multidrug-resistant tubercu-losis (MDR TB) threatens TB control worldwide. MDR TB is resistant to the most effective first-line agents, isoniazid (INH) and rifampin (RIF). The cornerstone of MDR TB diagnosis is culture and drug susceptibility testing (DST) of Mycobacterium tuberculosis isolates. Conventional methods for culture and first-line DST require weeks, causing delays in MDR TB diag-nosis and treatment, which in turn are associated with ad-vanced disease (6, 8), treatment failure (4), and transmission. Rapid molecular methods have been developed for the detec-tion of mutations that confer drug resistance (3, 5, 7), and several public health organizations have endorsed molecula