title: Evaluation of the microscopic observational drug susceptibility assay for rapid and efficient diagnosis of multi-drug resistant tuberculosis.
abstract: OBJECTIVE
  Tuberculosis (TB) is endemic in India and the burden of multi-drug-resistant tuberculosis (MDR-TB) is high. Early detection of MDR-TB is of primary importance in controlling the spread of TB. The microscopic observational drug susceptibility (MODS) assay has been described as a cost-effective and rapid method by which mycobacterial culture and the drug susceptibility test (DST) can be done at the same time.
  
  
  METHODS
  A total of 302 consecutive sputum samples that were received in an accredited mycobacteriology laboratory for conventional culture and DST were evaluated by the MODS assay.
  
  
  RESULTS
  In comparison with conventional culture on Lowenstein Jensen (LJ) media, the MODS assay showed a sensitivity of 94.12% and a specificity of 89.39% and its concordance with the DST by the proportion method on LJ media to isoniazid and rifampicin was 90.8% and 91.5%, respectively. The turnaround time for results by MODS was 9 days compared to 21 days by culture on LJ media and an additional 42 days for DST by the 1% proportion method. The cost of performing a single MODS assay was Rs. 250/-, compared to Rs. 950/- for culture and 1st line DST on LJ.
  
  
  CONCLUSIONS
  MODS was found to be a sensitive and rapid alternative method for performing culture and DST to identify MDR-TB in resource poor settings.
authors.affiliation: Department of Microbiology, Christian Medical College, Vellore, 632004, Tamil Nadu, India.
authors.forename: R P
authors.initials: RP
authors.lastname: Lazarus
authors.forename: S
authors.initials: S
authors.lastname: Kalaiselvan
authors.forename: K R
authors.initials: KR
authors.lastname: John
authors.forename: J S
authors.initials: JS
authors.lastname: Michael
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D000995:Antitubercular Agents / Q000494:pharmacology*; D005260:Female; D006801:Humans; D007194:India; D007538:Isoniazid / Q000494:pharmacology; D008297:Male; D008826:Microbial Sensitivity Tests / Q000379:methods; D008853:Microscopy / Q000379:methods*; D008875:Middle Aged; D009169:Mycobacterium tuberculosis / Q000187:drug effects* / Q000302:isolation & purification; D011446:Prospective Studies; D012293:Rifampin / Q000494:pharmacology; D012680:Sensitivity and Specificity; D013183:Sputum / Q000382:microbiology; D013997:Time Factors; D018088:Tuberculosis, Multidrug-Resistant / Q000175:diagnosis*; D055815:Young Adult
chemical_list: D000995:Antitubercular Agents; D007538:Isoniazid; D012293:Rifampin