The Yield of First Spot Double Slide Smears for the Diagnosis ofPulmonary Tuberculosis

Abstract

Background: Direct sputum smear microscopy is the cornerstone for the diagnosis of pulmonary tuberculosis (PTB) in resource-poor countries. However, the requirement for repeated visits to submit specimens and receive results is associated with considerable diagnostic delay, work load, patients drop-out and high expenses for patients. Although the World Health Organization (WHO) has recently changed its policy from spot morning spot (SMS) to spot morning (SM), the SM method still involves two days visits for a patient. The aim of this study was to evaluate the yield of first spot double slides smears for the diagnosis of PTB in high TB setting. Methods: A total of 362 patients who visited the out-patient department (OPD) of Dilla referral hospital and who were suspected of PTB were involved in the study. In addition SMS sputum samples were collected; double slides smears were prepared, stained by the Ziehl-Neelsen (ZN) method and 100 fields were examined under oil immersion objective for acid fast bacilli (AFB). Results: Of 362, 54 (14.92%) were smear-positives. Out of the 54 smear positive patients, 53 (98.15%) were positives by the first spot specimen. Additionally, 1 of 54 (1.85%) were positives by the morning specimen. Using the 2-day protocol (SMS) among 362 patients, 54 (14.92%) were smear positives by double slides and 53 (14.64%) by single slide smears. Whereas using the 1-day protocol (first spot); among 362 patients, 53 (14.64%) were smear positives both in double slides and single slide smears. Conclusion: The double slides smears from the first spot sputum samples appeared to be as effective as SMS strategy for the diagnosis of PTB though additional studies are required under various settings.