%0 Journal Article %A Mohammadzadeh, Alireza %A Farnia, Parisa %A Ghazvini, Kiarash %A Behdani, Mahdi %A Rashed, Tahereh %A Ghanaat, Javad %T Rapid and low-cost colorimetric method using 2,3,5-triphenyltetrazolium chloride for detection of multidrug-resistant Mycobacterium tuberculosis %D 2006 %J Journal of Medical Microbiology, %V 55 %N 12 %P 1657-1659 %@ 1473-5644 %R https://doi.org/10.1099/jmm.0.46442-0 %K MDR, multidrug-resistant %K INH, isoniazid %K RIF, rifampicin %K TTC, 2,3,5-triphenyltetrazolium chloride %I Microbiology Society, %X A rapid and inexpensive method for the detection of drug resistance in Mycobacterium tuberculosis is essential for the effective control of tuberculosis. The aim of this study was to evaluate a colorimetric method using 2,3,5-triphenyltetrazolium chloride (TTC) for antibiotic susceptibility testing of M. tuberculosis isolates. Eleven multidrug-resistant (MDR) isolates of M. tuberculosis and 12 isolates which were susceptible to rifampicin (RIF) and isoniazid (INH) were used. The test was performed with a critical concentration of 0.2 μg ml−1 for INH and 2.0 μg ml−1 for RIF in 7H9GC broth with 0.625 μg TTC ml−1. Each isolate was inoculated under these conditions and inspected daily for colour changes; the results were obtained after a mean of 4.9 days. The sensitivity and specificity of this method were 100 % and 92 %, respectively, for both antibiotics. Considering the speed, technical ease and cost-effectiveness of this method, the TTC assay is a good alternative method for drug susceptibility testing of M. tuberculosis isolates. %U https://www.microbiologyresearch.org/content/journal/jmm/10.1099/jmm.0.46442-0