Rapid and low-cost colorimetric method using 2,3,5-triphenyltetrazolium chloride for detection of multidrug-resistant Mycobacterium tuberculosis.

Alireza Mohammadzadeh, Parisa Farnia, Kiarash Ghazvini, Mahdi Behdani, Tahereh Rashed, Javad Ghanaat

Mycobacteriology Department, Gaem University Hospital, Mashhad University of Medical Science, Iran.

Journal of medical microbiology 2006 Dec

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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 microg ml(-1) for INH and 2.0 microg ml(-1) for RIF in 7H9GC broth with 0.625 microg 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.

Citation

Alireza Mohammadzadeh, Parisa Farnia, Kiarash Ghazvini, Mahdi Behdani, Tahereh Rashed, Javad Ghanaat. Rapid and low-cost colorimetric method using 2,3,5-triphenyltetrazolium chloride for detection of multidrug-resistant Mycobacterium tuberculosis. Journal of medical microbiology. 2006 Dec;55(Pt 12):1657-9