ABSTRACT
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.
Subject(s)
Humans , Sputum/microbiology , Tuberculosis, Pulmonary/diagnosis , Mycobacterium tuberculosis/isolation & purification , Mycobacterium tuberculosis/genetics , Brazil , DNA, Bacterial , False Negative ReactionsABSTRACT
Além de identificar os doentes com tuberculose (TB), é importante monitorar os genótipos de M. tuberculosis circulantes. Mesmo após a implantação do Xpert® MTB/RIF, o diagnóstico é ainda realizado apenas pela baciloscopia, que apresenta baixa sensibilidade, na maioria dos laboratórios. OBJETIVO: Utilizar análises de DNA para o diagnóstico e identificação dos genótipos circulantes em uma população do Rio Grande do Sul, Brasil. METODOLOGIA: Amostras clínicas foram analisadas pelo Detect-TB (Labtest,MG), por PCR em tempo real (Xpert® MTB/RIF) e comparados a baciloscopia. A genotipagem foi realizada por spoligotyping. RESULTADOS: A acurácia do Detect-TB para a identificação da TB foi similarao Xpert® MTB/RIF, sendo que o Detect-TB foi mais custo-efetivo quando utilizado em conjunto com a baciloscopia. Os genótipos LAM5, RDRio e like-Pinni2, relacionados a resistência ao tratamento, estavam sendo transmitidos neste grupo, e a maioria dos resistentes a isoniazida (78,5%)e dos resistentes a rifampicina (92,1%) apresentavam as mutações mais conhecidas. CONCLUSÃO: A aplicação de tecnologias de DNA pode auxiliar no controle de TB, tanto no diagnóstico rápido quanto na identificação de perfis resistentes, viabilizando tratamento adequado aos pacientes.
In addition to detecting patients with tuberculosis (TB), it is important tomonitor circulating M. tuberculosis genotypes. Even after the implantation of Xpert® MTB/RIF, the diagnosis is still based only by bacilloscopy, which have a low sensitivity, in most laboratories. OBJECTIVE: To use DNA analysis for diagnosis and identification of circulating genotypes in a population of Rio Grande do Sul, Brazil. METHODOLOGY: Clinical samples were analyzed by Detect-TB (Labtest,MG), real-time PCR (Xpert® MTB/RIF) and compared to bacilloscopy. Genotyping was performed by spoligotyping. RESULTS: The accuracy of Detect-TB was similar to Xpert® MTB / RIF, butDetect-TB was more cost-effective when used with bacilloscopy. The genotypesLAM5, RDRio and like-Pinni2, related to treatment resistance, were being transmitted among this group, and the majority of the resistant to isoniazid (78.5%) and the resistant to rifampicin (92.1%) presented themost known mutations. CONCLUSION: The application of DNA technologies can help in the controlof TB, both in rapid diagnosis and in the identification of resistant profiles, allowing adequate treatment to the patients.