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Free Content Rapid molecular detection of pulmonary tuberculosis in HIV-infected patients in Santiago, Chile

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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.

Keywords: HIV; Xpert® MTB/RIF; diagnosis; tuberculosis

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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  • The International Journal of Tuberculosis and Lung Disease publishes articles on all aspects of lung health, including public health-related issues such as training programmes, cost-benefit analysis, legislation, epidemiology, intervention studies and health systems research. The IJTLD is dedicated to the continuing education of physicians and health personnel and the dissemination of information on tuberculosis and lung health world-wide.

    Certain IJTLD articles are selected for translation into French, Spanish, Chinese or Russian. They are available on the Union website

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