title: Resazurin tube method: rapid, simple, and inexpensive method for detection of drug resistance in the clinical isolates of mycobacterium tuberculosis.
abstract: BACKGROUND
  Tuberculosis (TB) remains a serious public health problem worldwide. The emergence of drug resistance and multidrug resistance (MDR) has become the main threat to TB treatment and control programs. Rapid detection is critical for the effective treatment of patients. In recent times, a new method using the colorimetric indicator resazurin has been proposed for drug susceptibility of Mycobacterium tuberculosis.
  
  
  METHODS
  In this study, the resazurin reduction assay was adapted to screw cap tubes. Using the Resazurin Tube Method (RTM), a total of 100 clinical isolates were tested against Rifampicin (RIF) and Isoniazide (INH). By visual reading, the minimum inhibitory concentrations (MICs) were obtained after eight days. The results obtained were compared with the gold standard proportion method.
  
  
  RESULTS
  Excellent results were obtained for RTM with a sensitivity of 100% for both RIF and INH, with a specificity of 98.7 and 95.3%, respectively. Kappa is the measure of agreement between the RTM and proportion method (PM) for RIF and INH, which was found to be 0.972 and 0.935 for RIF and INH, respectively.
  
  
  CONCLUSIONS
  The RTM appears to be a reliable method for the rapid and simultaneous detection of MDR-TB and drug susceptibility testing (DST) of M. tuberculosis. It is simple, inexpensive, and with no biohazard risk involved.
authors.affiliation: Department of Microbiology, Bharati Vidyapeeth Deemed University, Medical College and Hospital, Sangli, Maharashtra, India.
authors.forename: Santosh S
authors.initials: SS
authors.lastname: Patil
authors.affiliation: Krishna Institute of Medical Sciences, Karad, Maharashtra, India.
authors.forename: Shivajirao T
authors.initials: ST
authors.lastname: Mohite
authors.affiliation: Department of Microbiology, Bharati Vidyapeeth Deemed University, Medical College and Hospital, Sangli, Maharashtra, India.
authors.forename: Sunanda A
authors.initials: SA
authors.lastname: Kulkarni
authors.affiliation: Department of Microbiology, Bharati Vidyapeeth Deemed University, Medical College and Hospital, Sangli, Maharashtra, India.
authors.forename: Usha S
authors.initials: US
authors.lastname: Udgaonkar
keywords: Drug susceptibility; Mycobacterium tuberculosis; RTM