Microbiological examination of three sputum specimens is proposed for the diagnosis in patients suspected to have pulmonary tuberculosis. The aim of this study was to determine the diagnostic efficacy of number of sputum specimens in the diagnosis of pulmonary tuberculosis. One hundred and four male patients, with a mean age of 24.4±10.8 years, who had pulmonary tuberculosis with at least three sputum specimens were enrolled into the study. Patients were divided into two goups as having cavitary pulmonary tuberculosis and non-cavitary pulmonary tuberculosis according to their chest X-rays. Smear positivity rates were 38% (40 patients), 48% (50 patients) and 55% (57 patients) for the first, first and/or second and first and/or second and/or third sputa, respectively. There were ten (10%) patients whose first sputum smear was negative but second smear was positive and seven (7%) patients whose first two sputum smears were negative but third sputum smear was positive. Culture positivity rates were 68% (71 patients), 77% (80 patients) and 84% (87 patients) for the first, first and/or second and first and/or second and/or third sputa, respectively. There were nine (%9) patients, whose first sputum culture was negative but second culture was positive and 7 (%7) patients whose first two sputum cultures were negative but third culture was positive. The differences between patients with cavitary and noncavitary pulmonary tuberculosis for smear and culture results were statistically significant (p<0.001 for both). Results of this study suggest that examination of three sputum specimens has more diagnostic efficacy than that of two or less sputum specimens.
Keywords: Pulmonary tuberculosis, sputum, diagnosis
