Isoniazid and rifampin drug susceptibility testing: application of 2,3,5-triphenyl tetrazolium chloride assay and microscopic-observation drug-susceptibility assay directly on Ziehl-Neelsen smear positive sputum specimens

Abstract The current study was aimed to evaluate the performance of direct 2,3,5-triphenyl tetrazolium chloride assay and direct microscopic observation drug susceptibility assay with indirect Löwenstein-Jensen proportion method directly on Ziehl-Neelsen smear positive sputum specimens. Methods Direct acid fast bacilli smear positive sputum specimens (n = 264) were subjected to isoniazid and rifampicin drug susceptibility testing by direct 2,3,5-triphenyl tetrazolium chloride assay, direct microscopic observation drug susceptibility assay, and the performances were compared with indirect Lö...