Evaluation of Same-day Microscopic Diagnosis Approaches for Pulmonary Tuberculosis: With Combination of Various Strategies in Existing Methods.

Abstract

Background:- Tuberculosis (TB) is a major cause of morbidity and mortality in relations to infectious disease. In 2011 WHO issued a policy statement recommending same-day diagnosis approach for sputum smear microscopy. Studies still clearly showed a limitation in detecting cases in same-day diagnosis approaches with conventional light microscopy. However, there is no adequate information whether introduction of bleach concentration in simple centrifugation method and using light-emitting diode-fluorescence microscopy (LED-FM). Objectives: - This study was conducted to assess the performance of same-day microscopic diagnosis approaches for pulmonary tuberculosis: with different combination of techniques and methods, at Jimma University Mycobacteriology Research Center, Southwest Ethiopia. Methods: - A comparative study was conducted among 126 tuberculosis presumptive patients from February 2016 to November 2016. From each participant, two spot sputum on the day of visit at one-hour interval and one morning and one spot on the next day were collected. Two direct smears were prepared from each specimen and two extra smears were prepared from pooled Spot-1 and spot-2 after concentrated with 5% bleach. The smears were stained by Ziehl‑Neelsen (ZN) and fluorescence (LED-FM) staining. Finally the remaining pools of sputum specimens were processed for culture on LJ medium. The sensitivities, specificities, likelihood ratio negative (LR-) and likelihood ratio positive (LR+) with their respective 95% confidence interval (CI) were determined using culture as the gold standard. Result: - From 126 selected participants only 120 were eligible for analysis. Of the 120, 34/120 (28.3 %) were culture-positive for M.tuberculosis complex. The same-day direct ZN strategy detected 25/120 (20.8 %) of TB suspected cases. It had significantly lower sensitivity 70.59 % compared to the conventional direct ZN strategy 88.23 %; (95CI: 77.41% - 99.07%). Same-day concentrated ZN strategy detected 32 (26.7 %) and increased the yield of same-day direct ZN strategy by 5.84 %. Same-day direct fluorescence strategy detected 30 (25 %). Same-day direct fluorescence strategy had comparable sensitivity and specificity compared to conventional direct fluorescence strategy and same-day concentrated fluorescence strategy. Same-day concentrated fluorescent strategy increased yield of Same-day direct fluorescence strategy by 1.67 % (2/120). Conclusions and recommendation: - Same-day direct ZN strategy had significant lower performance compared to the conventional direct ZN strategy. However, Same-day concentrated ZN strategies (Bleach treated Same-day) compensate the limitation of same-day direct ZN strategy. Same-day direct fluorescence strategy has comparable performance compared to conventional direct fluorescence strategy and same-day concentrated fluorescent strategy. Sameday diagnosis approaches can be applied with same-day concentrated ZN, same-day direct fluorescence strategy and same-day concentrated fluorescent strategy. Same-day direct fluorescence strategy better than the other strategies.