title: Rapid and low-cost colorimetric method using 2,3,5-triphenyltetrazolium chloride for detection of multidrug-resistant Mycobacterium tuberculosis.
abstract: 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.
authors.affiliation: Mycobacteriology Department, Gaem University Hospital, Mashhad University of Medical Science, Iran.
authors.forename: Alireza
authors.initials: A
authors.lastname: Mohammadzadeh
authors.affiliation: Iranian National Reference TB laboratory, National Research Institute of Tuberculosis & Lung Disease (NRITLD)/WHO Collaborating Centre, Tehran, Iran.
authors.forename: Parisa
authors.initials: P
authors.lastname: Farnia
authors.affiliation: Mycobacteriology Department, Gaem University Hospital, Mashhad University of Medical Science, Iran.
authors.forename: Kiarash
authors.initials: K
authors.lastname: Ghazvini
authors.affiliation: Mycobacteriology Department, Gaem University Hospital, Mashhad University of Medical Science, Iran.
authors.forename: Mahdi
authors.initials: M
authors.lastname: Behdani
authors.affiliation: Mycobacteriology Department, Gaem University Hospital, Mashhad University of Medical Science, Iran.
authors.forename: Tahereh
authors.initials: T
authors.lastname: Rashed
authors.affiliation: Mycobacteriology Department, Gaem University Hospital, Mashhad University of Medical Science, Iran.
authors.forename: Javad
authors.initials: J
authors.lastname: Ghanaat
mesh_terms: D000904:Antibiotics, Antitubercular / Q000494:pharmacology*; D001431:Bacteriological Techniques / Q000379:methods*; D024901:Drug Resistance, Multiple, Bacterial; D006801:Humans; D007538:Isoniazid / Q000494:pharmacology*; D008826:Microbial Sensitivity Tests / Q000379:methods*; D009169:Mycobacterium tuberculosis / Q000187:drug effects*; D012293:Rifampin / Q000494:pharmacology*; D012680:Sensitivity and Specificity; D013778:Tetrazolium Salts; D014376:Tuberculosis / Q000382:microbiology*
chemical_list: D000904:Antibiotics, Antitubercular; D013778:Tetrazolium Salts; C009591:triphenyltetrazolium; D007538:Isoniazid; D012293:Rifampin