Performance of a molecular assay to detect Mycobacterium tuberculosis complex DNA in clinical specimens: multicenter study in Brazil

BACKGROUND: In high tuberculosis (TB) burden countries, there are few data on the performance of new molecular commercialised assays developed locally. OBJECTIVE: To evaluate the performance of a new molecular commercialised assay for TB diagnosis (Detect-TB) in three laboratories. METHODS: A total of 302 sputum samples from an equal number of patients with presumptive diagnosis of pulmonary tuberculosis (PTB) were submitted for routine smear microscopy, culture, and Detect-TB assay at three different sites in Brazil (the cities of Caxias do Sul, São Paulo and Canoas). FINDINGS: Seventy four (24.7%) TB cases were diagnosed (65 bacteriologically confirmed). When compared to smear microscopy/culture results, the overall sensitivity and specificity of Detect-TB assay was 84.6% (CI 95%; 73.7-91.6) and 93.1% (CI 95%; 89.1-95.8), respectively. When compared to bacteriological and clinical diagnostic criteria, the sensitivity and specificity of Detect-TB assay was 74.3% (CI 95%; 63.3-82.9) and 92.9% (CI 95%; 88.7-95.6), respectively. Among the three sites - Caxias do Sul, São Paulo and Canoas - the sensitivity and specificity were respectively 94.7% and 97.8%; 71.4% and 93.9%, 82.1% and 88.9%. MAIN CONCLUSIONS: These findings suggest that the Detect-TB assay could be applied routinely in reference laboratories across different regions in Brazil.