Evaluation of two commercial nucleic acid amplification kits for detecting Mycobacterium tuberculosis in saliva samples

OBJECTIVE: The objective of this study was to evaluate the efficacy of two commercial nucleic acid amplification techniques to identify Mycobacterium tuberculosis in saliva. SUBJECTS AND METHODS: Fifty-two participants were recruited, 32 patients with a clinical and microbiological diagnosis of pulmonary tuberculosis and 20 healthy volunteers as controls. Three sputum samples were collected from each participant and were examined by direct bacilloscopy, cultured in liquid and solid media, and processed using the Mycobacterium tuberculosis direct (MTD) test for rRNA detection. One saliva sample was collected from each participant using conventional methods and was examined by direct bacilloscopy, cultured, and processed using the MTD test for rRNA detection and the FluoroType Mycobacterium tuberculosis assay for DNA detection. RESULTS: In saliva samples, the sensitivity, specificity, and positive and negative predictive values of the MTD test were 71.8%, 95%, 95.8%, and 67.8%, respectively. The values obtained with the FluoroType assay were 56.2%, 90%, 90%, and 56.2%, respectively. CONCLUSIONS: Our results indicate that when a sufficient volume of sputum cannot be obtained, saliva could be an alternative biological sample for the rapid diagnosis of pulmonary tuberculosis using commercial nucleic acid amplification techniques.