title: Rapid molecular detection of pulmonary tuberculosis in HIV-infected patients in Santiago, Chile.
abstract: METHODS
  Santiago, Chile, has a mean annual tuberculosis (TB) rate of 13 per 100 000 population; however, TB incidence in human immunodeficiency virus (HIV) infected individuals is at least 20 times higher.
  
  
  OBJECTIVE
  To assess the accuracy of rapid molecular testing for pulmonary  TB (PTB) detection in routine care in HIV-infected patients.
  
  
  METHODS
  Cross-sectional study, conducted prospectively in five hospitals between March 2010 and June 2011. HIV-positive subjects with suspected PTB provided sputum or mouth wash samples that were directly processed for acid-fast  smear, mycobacterial cultures and Xpert® MTB/RIF. Positive test results were reported on the same day.
  
  
  RESULTS
  We enrolled 166 subjects into the study; 50.6% provided two sputum samples, 33.1% only one sputum sample and 16.3% a mouth wash sample. The prevalence of TB was 8.1% (13/160).  Diagnostic sensitivity increased from 66.7% (95%CI 39.1-86.2) for acid-fast smear to 91.7% (95%CI 64.6-98.5) for Xpert MTB/RIF, with comparable specificity at 98.6% (146/148, 95%CI 95.2-99.6) and 99.3% (147/148, 95%CI 96.3-99.9). Xpert MTB/RIF allowed early detection  of rifampicin resistance in 16.6% of cases, with rapid adjustment to multidrug-resistant treatment.
  
  
  CONCLUSIONS
  Xpert MTB/RIF provided earlier TB diagnosis in 25% more cases than acid-fast smear alone. Its implementation should be considered for TB diagnosis in HIV-positive patients even  outside TB-endemic areas.
authors.affiliation: Facultad de Medicina, Pontificia Universidad Católica de Chile, Santiago, Chile. balcells@med.puc.cl
authors.forename: M E
authors.initials: ME
authors.lastname: Balcells
authors.forename: P
authors.initials: P
authors.lastname: García
authors.forename: L
authors.initials: L
authors.lastname: Chanqueo
authors.forename: L
authors.initials: L
authors.lastname: Bahamondes
authors.forename: M
authors.initials: M
authors.lastname: Lasso
authors.forename: A M
authors.initials: AM
authors.lastname: Gallardo
authors.forename: L
authors.initials: L
authors.lastname: Cifuentes
mesh_terms: D002677:Chile / Q000453:epidemiology; D003430:Cross-Sectional Studies; D042241:Early Diagnosis; D006678:HIV; D015658:HIV Infections / Q000150:complications* / Q000453:epidemiology; D006801:Humans; D025202:Molecular Diagnostic Techniques / Q000379:methods*; D009169:Mycobacterium tuberculosis / Q000302:isolation & purification*; D015995:Prevalence; D011446:Prospective Studies; D013183:Sputum / Q000382:microbiology*; D018088:Tuberculosis, Multidrug-Resistant / Q000150:complications / Q000175:diagnosis* / Q000382:microbiology; D014397:Tuberculosis, Pulmonary / Q000150:complications / Q000175:diagnosis* / Q000382:microbiology