Sputum smear microscopy in DOTS: Are three samples necessary? An analysis and its implications in tuberculosis control

OBJECTIVES: To assess relevance of spot morning spot (SMS) method of smear microscopy in tuberculosis control by directly observed treatment short course (DOTS). MATERIALS AND METHODS: Screening of smear microscopy results of 546 cases of pulmonary tuberculosis at our DOTS centre. RESULTS: Among 546 cases, 82% had all three samples positive for AFB, 98% had either morning sample or spot and morning sample positive. 2% had second spot sample positive. CONCLUSION: Examination of third sample, especially second spot sample, does not add significantly to the diagnostic yield. Examination of one spot and early morning samples were able to correctly diagnose 98% cases. This has strong implications in DOTS strategies.