Evaluation of microscopic observation drug susceptibility for drug susceptibility testing of mycobacterium tuberculosis in smear-positive sputum

Abstract

To evaluate microscopic observation drug susceptibility (MODS) for mycobacterium tuberculosis drug susceptibility in smear-positive sputum. Drug susceptibility of mycobacterium tuberculosis in 275 smear-positive sputum samples collected from TB patients were detected directly by MODS. The susceptibility of seven antimicrobials including streptomycin, isoniazid, rifampicin, ethambutol, levofloxacin, amikacin and capromycin were detected MODS. At the same time the sputum sample were cultured in MGIT 960 tube and the positive isolates were tested for drug susceptibility by MGIT 960 system. The results of MODS were analyzed and compared with that of MGIT 960. Of 275 smear-positive sputum, MODS detected 235 (85.45%). Results of MODS were obtained in a median time of 18 days (5 - 39 d). For the 235 MODS-positive samples, the compliance rates of MODS to MGIT of 7 drugs were 90.21% (212/235), 88.09% (207/235), 93.62% (220/235), 87.23% (205/235), 92.34% (217/235), 88.51% (208/235) and 86.81% (204/235) respectively. The sensitivity of MODS method were 83.33% (90/108), 85.11% (120/141), 90.74% (98/108), 85.71% (78/91), 86.73% (85/98), 76.92% (40/52) and 77.08% (37/48). The specificities of MODS method were 96.06% (122/127), 92.55% (87/94), 96.06% (122/127), 88.19% (127/144), 96.35% (132/137), 91.80% (168/183) and 89.30% (167/187) respectively. MODS is an optimal alternative method for direct and rapid drug susceptibility of sputum with high accuracy in a timely and affordable way in resource-limited settings.