Sensitivity and Specificity of Conventional Fluorescent Microscopy to diagnose Pulmonary Tuberculosis among Pulmonary tuberculosis symptomatics in Karimnagar

The conventional sputum microscopy is the standard method for detection of pulmonary tuberculosis is suspected cases. ZN staining is specific but less sensitive compared to fluorescent microscopy. The objective of the present study was to evaluate the sensitivity and specificity of ZN microscopy compared with conventional Fluorescent microscopy for examination of sputum in suspected pulmonary tuberculosis cases. A spot and early morning sample was collected in a sterile container from suspected cases of pulmonary tuberculosis. The sputum was processed under ZN staining, fluorescent staining and inoculated in Lowenstein Jensen media after decontamination. Of the 383 cases, culture results were available for all of them. Mycobacterium tuberculosis isolated in 102 (27%) of cases, no growth found in 269 (70%) cases, contamination observed in 12 (3%) patients. No Non tuberculous mycobacteria isolated. More than half 53 out of 102 cases of the culture positive samples were of 2 + culture grading. Under solid culture 26.6% (102 cases) were positive and 22.2% (85 cases), 17.8% (68 cases) reported conventional fluorescent microscopy and ZN microscopy respectively. The sensitivity and specificity of ZN microscopy to culture was 62.7% and 98.5% respectively similarly when the sensitivity and specificity of conventional fluorescent microscopy with culture was compared the results were 78.14% of Sensitivity and 98.14% of Specificity were obtained. Ziehl Neelsen microscopy is less sensitive compared to fluorescent microscopy. Byreplacing the existing ZN microscopy and utilizing fluorescence microscopy, smear positive pulmonary tuberculosis case detection may be enhanced as the fluorescent microscopy is 16% more sensitive compared to ZN microscopy. The fluorescent microscopy is found to reduce the examination time by half and will help in screening more number of slides in high work load microscopy centers.