Concordance between microscopic and molecular detection of Mycobacterium tuberculosis in hospitalized patients with suspected pulmonary tuberculosis in Peltier General Hospital, Djibouti

Abstract

Background: Tuberculosis (TB) remains a significant public health issue, and Djibouti is still one of the nations with a high TB burden, with a forecasted incidence rate of 224 cases per 100,000 people in 2020. Objectives: To compare the Ziehl-Neelsen (ZN) stain direct smear microscopy with the GeneXpert (Xpert MTB/RIF assay) as the gold standard for diagnosing patients with suspected pulmonary tuberculosis (PTB). Material and method: A health facility-based cross-sectional study was conducted on hospitalized patients at Peltier General Hospital from March to July 2022. A total of 153 samples (including bronchoalveolar lavage (BAL) and sputum) collected from presumptive TB patients were tested. Results: Out of the 153 samples analyzed by GeneXpert and ZN smear microscopy, 29 (19.0%) were detected by GeneXpert and 23 (15.0%) were positive by ZN smear microscopy. ZN smear microscopy had sensitivity, specificity, positive predictive value (PPV), and negative predictive value (NPV) that were 79.31%, 100%, 100%, and 95.38%, respectively. Conclusion: This study concluded that ZN smear had a slightly poor sensitivity for determining the presence of PTB; consequently, we continue to advise GeneXpert testing whenever it is possible to prevent prolonged morbidity in those affected and to prevent the direct as well as indirect expenses of missing the diagnosis of smear-negative PTB.