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Setting: faster alternative techniques are required to improve the diagnosis and control of pulmonary tuberculosis., Objective: To evaluate the sample quality in the performance of PCR for diagnosis of pulmonary tuberculosis., Method: during one year, sputum samples were collected from 72 pulmonary tuberculosis patients and 12 non-tuberculosis controls, which were admitted to the Nereu Ramos hospital, Florianópolis city, Brazil. The samples were subjected to Ziehl-Neelsen-stained sputum smear microscopy and Lowestein-Jensen medium culture, which were defined as gold standard tests for mycobacteria, and polymerase chain reaction (PCR). Those samples that presented more than 40% of viable cells and less than 25% of epithelial cells were defined as high quality samples., Results: PCR showed sensitivity of 55.6%, specificity of 41.7%, positive predictive value of 85.1%, negative predictive value of 13.5%, and accuracy of 53.6%. High quality samples showed sensitivity of 72.4%, specificity of 50%, positive predictive value of 91.3%, negative predictive value of 20%, and accuracy of 69.7%. Low quality samples showed sensitivity of 44.2%, specificity of 37.5%, positive predictive value of 79.2%, negative predictive value of 11.1%, and accuracy of 43.1%., Conclusion: use of high quality samples improved significantly the PCR performance, especially on their sensitivity and positive predictive values.

Induced sputum is a useful technique for assessing airway inflammation, but its role in the diagnosis of lung disease in immunosuppressed patients needs further investigation. This study compared the use of induced sputum and BAL in the diagnosis of pneumocystosis, in HIV patients. From January 1, 2001, to December 30, 2002, HIV-positive patients older than 14 were evaluated at a hospital in Florianópolis, Santa Catarina, Brazil. Patients with respiratory symptoms for seven days or longer, with a normal or abnormal chest X-ray, and those without respiratory symptoms but with an abnormal chest X-ray, were included in the study. All patients were submitted to clinical, radiological and laboratory evaluation, after which induced sputum and bronchoscopy with bronchoalveolar lavage were carried out. The samples were subjected to the following techniques: Gram and Ziehl-Neelsen staining, quantitative culture growth for pyogenic bacteria, direct staining for fungi, culture growth for mycobacteria and fungi, and Grocott-Gomori staining for Pneumocystis jiroveci, as well as total and differential cell counts. The samples with P. jiroveci were selected, as well as the samples for which no etiologic agents were observed. Forty-five patients with a mean age of 34.6, 38 male and 40 Caucasian, comprised the subjects. Interstitial infiltrate was the most frequent radiological pattern (53.3%). The induced sputum sensitivity was 58.8%, specificity 81.8%, predictive positive value 90.9%, predictive negative value 39.1% and accuracy 64.4%, for the diagnosis of pneumocystosis, compared with BAL. Based on these data, induced sputum is a useful technique for the diagnosis of pneumocystosis in HIV patients.