The clinical utility of induced sputum for the diagnosis of bacterial community-acquired pneumonia in HIV-infected patients: a prospective cross-sectional study

Abstract

Bacterial pneumonias have been overcoming pneumocytosis in frequency. Controversy still remains about how to manage immunocompromised patients and those with lung diseases. Sputum analysis is a noninvasive and simple method, and when interpreted according to specific criteria it may help with diagnosis. We conducted a study to evaluate sensitivity, specificity, positive and negative predicted values, and the accuracy of induced sputum (IS) for bacterial community-acquired pneumonia diagnosis in HIV-positive patients. This cross sectional study evaluated a diagnostic procedure in a reference hospital for HIV patients in Florianópolis, SC, Brazil. From January 1, 2001 to September 30, 2002, 547 HIV-positive patients were analyzed and 54 inpatients with pulmonary infection were selected. Bronchoalveolar lavage (BAL) and transbronchial lung biopsy (TBLB) were considered the gold standards. Gram stains and quantitative cultures of IS and BAL were obtained. The cut-offs for quantitative cultures were 10(6) CFU/mL for IS and 10(4) CFU/mL for BAL. The mean age was 35.7 years, 79.6% were males and 85.2% were caucasians. The mean lymphocyte count was 124.8/mm(3). Bacterial pneumonia was diagnosed in 20 patients. The most prevalent bacteria was Streptococcus pneumoniae. Considering IS for the diagnosis of bacterial pneumonia, sensitivity was 60%, specificity 40%, the positive predictive value was 80%, negative predictive value 20% and accuracy 56%. IS with quantitative culture can be helpful for the diagnosis of bacterial pneumonia in HIV-positive patients.