Rapid Diagnosis of Tuberculosis and Multidrug Resistance by the Microscopic-Observation Drug-Susceptibility Assay

Rationale: Mortality is exceedingly high and rapid among patients infected with HIV and tuberculosis (TB), in part because of limited access to appropriate TB diagnostics. The microscopic observation drug-susceptibility (MODS) assay is a simple, rapid, low-cost test for TB and multidrug-resistant (MDR) TB, but data in individuals infected with HIV and in Africa are limited.Objectives: To evaluate the MODS assay in a high-HIV-prevalence setting.Methods: We performed a prospective diagnostic accuracy study of consecutive adults suspected to have TB from outpatient and inpatient settings at a district hospital in rural South Africa. Sputum was tested by concentrated smear microscopy; agar (Middlebrook 7H11) and liquid (mycobacterial growth indicator tube) culture; and the MODS assay. Drug-susceptibility testing (DST) was by indirect 1% proportion method and MODS. Reference standard for Mycobacterium tuberculosis detection was growth on Middlebrook or mycobacterial growth indicator tube culture; 1% proportion...