Same day sputum microscopy for screening of pulmonary tuberculosis: Its accuracy and usefulness in comparison with conventional method

sputum microscopy is the primary diagnostic tool for screening pulmonary tuberculosis (PtB) suspects in tB prevalent countries. Our study had evaluated the 'front loading' or 'same day' sputum microscopy feasibility to screen clinically suspected PTB cases, in comparison to standard method of smear microscopy. In this hospital based cross-sectional study, three sputum specimens i.e., two consecutive spot samples collected in one hour interval on the first day of visit and a single sputum sample was collected on the next day early morning from 312 randomly selected adults suspected for PtB. sputum samples were cultured on lowenstein-Jensen (lJ) medium and stained by auramine O method and examined under LED-fluorescence microscopy. Out of 312 presumptive PTB patients, 43 (13.8%) were smear-positive by front loading method and 46 (14.7%) by standard method respectively. Considering LJ media culture as the gold standard test, the sensitivity was 83.7% and 89.8% respectively for front loading and the standard sputum microscopy and specificity was 99.2% by both methods. the statistical difference was insignificant between two methods of sputum microscopy (p-value > 0.05 by McNemar's test). In health care settings of high burden countries same day sputum microscopy could be an acceptable method to screen the suspects of pulmonary tuberculosis and complete the diagnosis procedure on the first day of visit, which will decrease patients' drop-out from the diagnostic procedure and initiate treatments as soon as possible.