Evaluation of rapid MTT tube method for detection of drug susceptibility of Mycobacterium tuberculosis to rifampicin and isoniazid.
Indian J Med Microbiol
;
2008 Jul-Sep; 26(3): 222-7
Article
in English
| IMSEAR
| ID: sea-54041
ABSTRACT
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(0.2microg/mL) or RIF(1microg/mL), another as inoculum control and third as blank control. These were incubated at 37 degrees 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 specificity 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 specificity 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.
Full text:
Available
Index:
IMSEAR (South-East Asia)
Main subject:
Rifampin
/
Temperature
/
Tetrazolium Salts
/
Thiazoles
/
Time Factors
/
Humans
/
Microbial Sensitivity Tests
/
Sensitivity and Specificity
/
Culture Media
/
Drug Resistance, Bacterial
Type of study:
Diagnostic study
/
Evaluation studies
Language:
English
Journal:
Indian J Med Microbiol
Journal subject:
Microbiology
Year:
2008
Type:
Article
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