Effects of household bleach on sputum smear microscopy to concentrate acid fast bacilli for the diagnosis of pulmonary tuberculosis.

Tuberculosis (TB) is one of the major public health problem among contagious diseases in Pakistan. TB diagnosis mainly depends on sputum smear microscopy. The main objective of this study was to evaluate the effects of household bleach on sputum smear microscopy to concentrate acid fast bacilli for the diagnosis of pulmonary tuberculosis. Sputum specimens of 200 suspected TB patients were collected for the study. Smears were prepared from the purulent part of sputum sample before and after bleach treatment, heat fixed and stained with the ZN technique. The obtained data were analyzed by chi-squared test using SPSS software. Out of 200 isolates, 22 (11%) patients had positive smears for acid fast bacilli (AFB) by direct ZN staining. After treatment with household bleach (NaOCL) and centrifugation, the number of AFB positive patients were increased from 22 (11%) to 37 (18.5%). The bleach-concentration method for sputum samples significantly increased the TB detection rate as compared to direct sputum smear microscopy. Thus, a shift from direct sputum microscopy to bleach-concentration technique should be considered a better method for detection of AFB in sputum through smear microscopy.