title: A rapid and low-cost microscopic observation drug susceptibility assay for detecting TB and MDR-TB among individuals infected by HIV in South India.
abstract: BACKGROUND
  The converging epidemics of HIV and tuberculosis (TB) pose one of the greatest public health challenges of our time. Rapid diagnosis of TB is essential in view of its infectious nature, high burden of cases, and emergence of drug resistance.
  
  
  OBJECTIVE
  The purpose of this present study was to evaluate the feasibility of implementing the microscopic observation drug susceptibility (MODS) assay, a novel assay for the diagnosis of TB and multi-drug-resistant tuberculosis (MDR-TB) directly from sputum specimens, in the Indian setting.
  
  
  METHODS
  This study involved a cross-sectional, blinded assessment of the MODS assay on 1036 suspected cases of pulmonary TB in HIV-positive and HIV-negative patients against the radiometric method, BD-BACTEC TB 460 system.
  
  
  RESULTS
  Overall, the sensitivity, specificity, positive predictive value, and negative predictive value of the MODS assay in detecting MTB among TB suspected patients were 89.1%, 99.1%, 94.2%, 95.8%, respectively. In addition, in the diagnosis of drug-resistant TB, the MODS assay was 84.2% sensitive for those specimens reporting MDR, 87% sensitivity for those specimens reporting INH mono-resistance, and 100% sensitive for specimens reporting RIF mono-resistance. The median time to detection of TB in the MODS assay versus BACTEC was 9 versus 21 days (P<0.001).
  
  
  CONCLUSIONS
  Costing 5 to 10 times lesser than the automated culture methods, the MODS assay has the potential clinical utility as a simple and rapid method. It could be effectively used as an alternative method for diagnosing TB and detection of MDR-TB in a timely and affordable way in resource-limited settings.
authors.affiliation: Infectious Diseases Laboratory, YRG Centre for AIDS Research and Education (YRG CARE), Chennai, India.
authors.forename: S
authors.initials: S
authors.lastname: Solomon
authors.forename: P
authors.initials: P
authors.lastname: Balakrishnan
authors.forename: R
authors.initials: R
authors.lastname: Vignesh
authors.forename: G
authors.initials: G
authors.lastname: Waldrop
authors.forename: S S
authors.initials: SS
authors.lastname: Solomon
authors.forename: K G
authors.initials: KG
authors.lastname: Murugavel
authors.forename: N
authors.initials: N
authors.lastname: Kumarasamy
authors.forename: T
authors.initials: T
authors.lastname: Yepthomi
authors.forename: S
authors.initials: S
authors.lastname: Poongulali
authors.forename: C R
authors.initials: CR
authors.lastname: Swathirajan
authors.forename: V
authors.initials: V
authors.lastname: Sreenivasan
authors.forename: C
authors.initials: C
authors.lastname: Chandrasekar
authors.forename: J
authors.initials: J
authors.lastname: Suriakumar
authors.forename: A
authors.initials: A
authors.lastname: Mahilmaran
authors.forename: G
authors.initials: G
authors.lastname: Manoharan
authors.forename: D A J
authors.initials: DA
authors.lastname: Moore
mesh_terms: D000328:Adult; D000995:Antitubercular Agents / Q000494:pharmacology*; D003365:Costs and Cost Analysis; D024881:Drug Resistance, Bacterial; D015658:HIV Infections / Q000150:complications*; D006801:Humans; D007194:India; D008297:Male; D008826:Microbial Sensitivity Tests / Q000191:economics / Q000379:methods; D008853:Microscopy / Q000191:economics / Q000379:methods*; D009169:Mycobacterium tuberculosis / Q000187:drug effects / Q000302:isolation & purification*; D011237:Predictive Value of Tests; D012680:Sensitivity and Specificity; D013183:Sputum / Q000382:microbiology; D014376:Tuberculosis / Q000175:diagnosis* / Q000382:microbiology*
chemical_list: D000995:Antitubercular Agents