Improved microscopic diagnosis of smear positive tubercle bacilli among patients suspected of Pulmonary Tuberculosis in Western Region of Nepal

Abstract

Tuberculosis, caused by a bacterium called Mycobacterium tuberculosis, is the largest cause of death from a single infectious disease and is still a major health problem worldwide. The infection spreads by inhaling droplets of mucus that have been expelled by an infected person. Factors associated with infectivity include bacillary load, severity of coughing, proximity to the patient and the duration of anti-TB therapy. A cross-sectional study was carried out where two dependent variables (direct and concentration method) were compared with other independent variables. A total of 177 samples were collected from patients visiting OPD of western regional 
tuberculosis centre, Pokhara. The sputum was collected in sterile container and transferred to the laboratory of SHAS, Pokhara University and those samples that were delayed for processing were stored at 2-8°C in refrigerator. The detection of tubercle bacilli was done by direct microscopy and sedimentation method. Data were analyzed by using SPSS v 17.0. Concentration method increases the detection rate of tubercle bacilli (14.1%) as compared with direct microscopy (12.4%). Concentration method is more effective in TB diagnosis in resource limited areas as it increases the positivity rate than direct microscopy. There were no significant relation between 
tuberculosis and other independent variables except smoking and drinking (p=0.0001). Despite being rapid, cost effective and specific for tuberculosis in terms of sensitivity as well as in positivity rate for smear positive cases, AFB staining is less effective compared to the Concentration by using hypochlorite. Bleach sedimentation microscopy is an effective, simple method to improve the yield of smear microscopy.