Background and purpose: Direct smear microscopy is the most common method of detecting tuberculosis with 70% sensitivity in best conditions, therefore, researches have always focused on improving the sensitivity of sputum smear. This study aimed at comparing the diagnostic value of sputum smear using light microscopy and fluorescence microscopy without sodium hypochlorite in patients with suspected pulmonary tuberculosis.

Materials and methods: A cross-sectional study was performed in 195 patients suspected of pulmonary tuberculosis attending Zahedan Booali Hospital who were selected via purposive sampling. Three sputum specimens were obtained from each patient and microscopic examinations were done using the Ziehl–Neelsen staining, auramine-rhodamine staining and Leuven Stein culturing. For smear microscopy, two sets of sputum smears were prepared from each sample (with and without sodium hypochlorite). Finally, the results of smear microscopy and sputum culture were compared.

Results: In direct smear using the Ziehl–Neelsen with and without sodium hypochlorite 69 (35%) and 63 (32%) patients were found positive, respectively and in auramine-rhodamine staining with and without adding sodium hypochlorite 71 (36%) and 66 (33%) cases were found positive, respectively. Fluorescent microscope with and without sodium hypochlorite increased the diagnostic value of direct smear compared to optical microscopy but this increase was not statistically significant.

Conclusion: The diagnostic value of sputum smear microscopy using fluorescent sodium hypochlorite in patients with suspected pulmonary tuberculosis was more than other diagnostic methods.