Martin, A. et al. Multicenter study of MTT and resazurin assays for testing susceptibility to first-line anti-tuberculosis drugs. Int. J. Tuberc. Lung Dis. 9, 901-906 (original) (raw)
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Resazurin assay for rapid drug susceptibility testing of Mycobacterium tuberculosis
IP Innovative Publication Pvt. Ltd., 2018
Introduction: Tuberculosis, a disease of antiquity continues to cause high morbidity and mortality. In Sustainable Development Goals and End Tb Strategy proposed by WHO includes Drug Susceptibility Testing as major component. Conventional methods are time consuming and molecular methods are rapid but expensive and demanding. Resazurin assay is a rapid colorimetric redox indicator method of Drug Susceptibility Testing. Materials and Methods: 67 strains of M. tuberculosis isolated from pulmonary tuberculosis patients were tested using indirect absolute concentration method by resazurin assay and compared with drug incorporated Lowenstein – Jensen media for Isoniazid and Rifamycin. Results: There was 91.5 % and 91.7% concordance between both methods for INH and Rifamycin respectively. Resazurin assay for INH was 100% sensitive and 61.54% specific. Sensitivity and specificity for RMP was 98.04% and 62.5% respectively. The duration required for INH was 7.0 ± 2.07 and for RMP 6.58 ± 1.58 days. Conclusions: Resazurin assay is sensitive, rapid, cheap, technically simple drug susceptibility method. Keywords: M. tuberculosis, resazurin assay, drug susceptibility.
Indian Journal of Medical Microbiology, 2008
Purpose: To evaluate MTT method for detection of drug resistance to rifampicin and isoniazid in M.tuberculosis. This method utilises the ability of viable mycobacterial cells to reduce MTT(3-4,5-dimethylthiazol-2-yl-2, 5-diphenyl tetrazolium bromide). Methods: The method was standardised with known resistant and sensitive strains of M.tuberculosis and was then extended to 50 clinical isolates. An inoculum of 10 7 cfu/mL was prepared in Middlebrook 7H9 medium supplemented with oleic acid, albumin, dextrose and catalase. For each drug three tubes were used, one with INH(0.2μg/ mL) or RIF(1μg/mL), another as inoculum control and third as blank control. These were incubated at 37°C for four and seven days respectively for RIF and INH after which MTT assay was performed. Results were read visually and by colorimeter at 570 nm. Relative optical density unit (RODU) of 0.2 was taken as cut off. Results were compared with drug sensitivity obtained by proportion method using LJ medium. Results: For rifampicin, concordance with proportion method was 90% by visual and 94% by RODU. Sensitivity and speciÞ city was 86.8% and 100% respectively by visual method and 95.2% and 87.5% respectively by RODU. For Isoniazid, concordance was 94% and sensitivity and speciÞ city was 94.7 and 91.7% respectively by both visual and RODU. Conclusions: MTT assay proved to be rapid and cheap method for performing drug sensitivity of M.tuberculosis.
Brazilian Journal of Microbiology, 2008
Tuberculosis remains as a serious infection disease of worldwide distribution, with high morbidity and mortality, mainly in low socioeconomic condition countries. The state of emergency of tuberculosis caused by the resistant and multidrug-resistant (MDR) strains, became the main threat to the tuberculosis treatment and control programs. A fast detection method for the resistant strains will allow the implementation of an adequate treatment and contribute for controlling the dissemination of these resistant strains. This study evaluated the performance of the nitrate reductase assay in solid (NRA-LJ) and liquid (NRA-7H9) media, to determine the susceptibility to first line anti-tuberculosis drugs: isoniazid (INH), rifampicin (RMP), ethambutol (EMB) and streptomycin (SMR). Both methods NRA-LJ and NRA-7H9 were evaluated among 18 strains with a known susceptibility profile. The resazurin microtiter assay (REMA) was performed as a reference method. One hundred percent of accordance was observed between NRA-7H9 and REMA for the four tested drugs. When the NRA-LJ method was compared to REMA, the sensitivity and the specificity to INH, RMP, EMB and SMR were 100%, 100 %, 85.7%, 76.9% and 80%, 100%, 75% and 80%, respectively. From the 57 clinical isolates of M. tuberculosis evaluated by NRA-7H9 and REMA, 56 (98.2%) were sensitive to all antibiotics tested (INH, RMP, EMB and SMR) by the NRA-7H9 method, while three of these strains were resistant to INH by REMA. One strain showed resistance to INH and RMP for both methods, and MIC of 1.0 µg/ml to INH for both methods, while MIC of 1.0 and 2.0 µg/ml to RMP for REMA and NRA-7H9, respectively. The three assays showed a high level of agreement for rapid detection of rifampicin and isoniazid resistance. Regarding rapidness, the detection of color change in the NRA method is within instants as compared to the overnight incubation required for the REMA test. NRA might represent an inexpensive and alternative assay for rapid detection of resistance in low-income countries.
Indian Journal of Medical Microbiology, 2008
Purpose: To evaluate MTT method for detection of drug resistance to rifampicin and isoniazid in M.tuberculosis. This method utilises the ability of viable mycobacterial cells to reduce MTT(3-4,5-dimethylthiazol-2-yl-2, 5-diphenyl tetrazolium bromide). Methods: The method was standardised with known resistant and sensitive strains of M.tuberculosis and was then extended to 50 clinical isolates. An inoculum of 10 7 cfu/mL was prepared in Middlebrook 7H9 medium supplemented with oleic acid, albumin, dextrose and catalase. For each drug three tubes were used, one with INH(0.2μg/ mL) or RIF(1μg/mL), another as inoculum control and third as blank control. These were incubated at 37°C for four and seven days respectively for RIF and INH after which MTT assay was performed. Results were read visually and by colorimeter at 570 nm. Relative optical density unit (RODU) of 0.2 was taken as cut off. Results were compared with drug sensitivity obtained by proportion method using LJ medium. Results: For rifampicin, concordance with proportion method was 90% by visual and 94% by RODU. Sensitivity and speciÞ city was 86.8% and 100% respectively by visual method and 95.2% and 87.5% respectively by RODU. For Isoniazid, concordance was 94% and sensitivity and speciÞ city was 94.7 and 91.7% respectively by both visual and RODU. Conclusions: MTT assay proved to be rapid and cheap method for performing drug sensitivity of M.tuberculosis.
The international journal of tuberculosis and lung disease : the official journal of the International Union against Tuberculosis and Lung Disease, 2007
Multidrug-resistant (MDR) tuberculosis (TB) can jeopardise the success of national TB control programmes. Rapid, simple drug susceptibility tests applicable in developing countries would allow earlier treatment of patients with MDR infections. To test the feasibility and performance of the resazurin microtitre assay (REMA) as an indirect test for detecting isoniazid (INH) and rifampicin (RMP) resistance of Mycobacterium tuberculosis strains in Madagascar. Study comparing the sensitivity and specificity of the REMA plate test with the Löwenstein-Jensen proportion method for determining the resistance of M. tuberculosis strains to INH and RMP. The sensitivity and specificity of the resazurin test were studied in 77 strains and were respectively 95% and 97.3% for the detection of INH resistance, and 95% and 100% for the detection of RMP resistance. The sensitivity and specificity for the identification of MDR strains were respectively 89% and 100%. The resazurin test is sensitive and s...
Egyptian Journal of Chest Diseases and Tuberculosis, 2013
Background: Many developed countries need a diagnostic test that is accurate, rapid, and economical in detecting multidrug-resistant tuberculosis. This study aims to evaluate Resazurin Microtiter Assay Plate in detecting susceptibilities of multidrug resistant Mycobacterium tuberculosis to second line anti tuberculous drugs. Methods: Susceptibility of multidrug resistant M. tuberculosis was evaluated against 5 second line anti tuberculous drugs by the colorimetric method using the Resazurin Microtiter Assay Plate Testing (REMA). Results: Drug susceptibility testing for the second-line drugs was performed for 34 MDR M. tuberculosis isolates isolated from 40 sputum samples. Results of REMA were available after 8 days of incubation. The agreement between the two tests for para-aminosalicylic acid, ethionamide, ofloxacin, kanamycin monosulfate and cycloserine was found to be 97.05%, 94.11%, 97.05%, 97.05% and 100%, respectively. The efficacy of REMA plate assay for PAS, ETH, OFX, KAN and CYL was 97.05%, 94.11%, 97.05%, 97.05% and 100%, respectively. Conclusion: Resazurin test was found to be reliable, simple to perform for the rapid detection of anti-tuberculous drug resistance and economically inexpensive.
Antimicrobial Agents and Chemotherapy, 2003
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