Evaluation of seven tests for the rapid detection of multidrug-resistant tuberculosis in Uganda.
METHODS
National Tuberculosis (TB) Reference Laboratory and Department of Medical Microbiology, College of Health Sciences, Makerere University, Kampala, Uganda.


OBJECTIVE
To evaluate head-to-head rapid tests for drug susceptibility testing (DST) of Mycobacterium tuberculosis against rifampicin (RMP) and isoniazid (INH) in a resource-limited setting.


METHODS
Thirty-one well-characterised strains of M. tuberculosis were tested with the nitrate reductase assay (NRA), microscopic observation drug susceptibility (MODS), MGIT 960 (Mycobacterium Growth Indicator Tube 960), Genotype MTBDRplus, Alamar blue, MTT and resazurin assays. The proportion method on Löwenstein-Jensen medium was used as the reference test.


RESULTS
NRA correctly identified the resistant strains, with 100% sensitivity and specificity. MGIT 960 detected all multidrug-resistant strains but missed one RMP-monoresistant strain. Genotype MTBDRplus detected all RMP-resistant strains, but the sensitivity for detection of INH resistance was lower (88%). Sensitivity and specificity ranged from 86% to 100% for MODS and from 57% to 100% for the Alamar blue, MTT and resazurin assays. Test results were obtained within 2-14 days.


CONCLUSIONS
In the study setting, NRA, MGIT 960 and Genotype MTBDRplus gave excellent detection of multidrug-resistant tuberculosis, with significantly shorter time to results compared to conventional testing.
Bwanga
F
F
Department of Medical Microbiology, College of Health Sciences, Makerere University, Kampala, Uganda.
Joloba
M L
ML
Haile
M
M
Hoffner
S
S
D000995:Antitubercular Agents / Q000494:pharmacology*; D006801:Humans; D007538:Isoniazid / Q000494:pharmacology; D008826:Microbial Sensitivity Tests; D009169:Mycobacterium tuberculosis / Q000187:drug effects* / Q000302:isolation & purification; D012293:Rifampin / Q000494:pharmacology; D012680:Sensitivity and Specificity; D013997:Time Factors; D018088:Tuberculosis, Multidrug-Resistant / Q000175:diagnosis* / Q000188:drug therapy / Q000382:microbiology; D014454:Uganda
D000995:Antitubercular Agents; D007538:Isoniazid; D012293:Rifampin