Comparative evaluation of the microplate nitrate reductase assay and the rezasurin microtitre assay for the rapid detection of multidrug resistant Mycobacterium tuberculosis clinical isolates

• Published in: Memórias do Instituto Oswaldo Cruz Vol. 107; no. 5; pp. 578 - 581
• Main Authors: Coban, Ahmet Yilmaz, Uzun, Meltem, Akgunes, Alper, Durupinar, Belma
• Format: Journal Article
• Language: English
• Published: Brazil Fundação Oswaldo Cruz, Fiocruz 01.08.2012; Instituto Oswaldo Cruz, Ministério da Saúde; Fundação Oswaldo Cruz (FIOCRUZ)
• Subjects: Antitubercular Agents - pharmacology; Drug Resistance, Multiple, Bacterial - drug effects; Humans; Isoniazid - pharmacology; MIC determination; Microbial Sensitivity Tests - methods; microplate nitrate reductase assay; Mycobacterium tuberculosis; Mycobacterium tuberculosis - drug effects; Mycobacterium tuberculosis - isolation & purification; Nitrate Reductase - metabolism; Oxazines - metabolism; PARASITOLOGY; Predictive Value of Tests; Reagent Kits, Diagnostic; rezasurin microtitre assay; Rifampin - pharmacology; Sensitivity and Specificity; TROPICAL MEDICINE; Tuberculosis, Multidrug-Resistant - microbiology; Xanthenes - metabolism; rezasurin microtitre assay; microplate nitrate reductase assay; Mycobacterium tuberculosis; MIC determination
• ISSN: 1678-8060; 0074-0276; 1678-8060; 0074-0276
• DOI: 10.1590/S0074-02762012000500002

The microplate nitrate reductase assay (MNRA) and the rezasurin microtitre assay (REMA) were used for the susceptibility testing of 73 clinical isolates and the results were compared with those that were obtained using the Bactec 460 TB and Bactec MGIT 960 systems. The REMA and the MNRA were performed in 96-well plates. For the REMA, the concentrations of isoniazid (INH) and rifampicin (RIF) ranged from 1.0-0.01 μg/mL and 2.0-0.03 μg/mL, respectively. For the MNRA, the INH concentration was between 1.0-0.03 μg/mL and the RIF concentration was between 2.0-0.06 μg/mL. For the MNRA, the sensitivity, specificity, positive predictive value, negative predictive value and INH/RIF agreement were 100/95.6, 97.6/100, 96.8/100, 100/98 and 98.6/98.6, respectively, and for the REMA, they were 100/91.3, 90.4/100, 88.5/100, 100/96.1 and 94.5/97.2, respectively. Our data suggest that these two rapid, low-cost methods may be inexpensive, alternative assays for the rapid detection of multidrug resistant tuberculosis in low-income countries.