Rapid molecular detection of pulmonary tuberculosis in HIV-infected patients in Santiago, Chile
Abstract:SETTING: 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.
DESIGN: 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.
CONCLUSION: 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.
Document Type: Research Article
Affiliations: 1: Facultad de Medicina, Pontificia Universidad Católica de Chile, Santiago, Chile 2: Hospital San Juan de Dios, Santiago, Chile 3: Hospital Lucio Córdova, Santiago, Chile 4: Facultad de Medicina, Pontificia Universidad Católica de Chile, Santiago, Chile; Hospital Sótero del Río, Santiago, Chile 5: Hospital del Salvador, Santiago, Chile
Publication date: October 1, 2012
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