Desta, Kassu (Assistant Professor)Assefa, Dereje2018-06-272023-11-062018-06-272023-11-062014-06http://etd.aau.edu.et/handle/123456789/4261Background: TB detection rate remains critical stumbling block for TB control. Though conventional methods for TB detection exist; GeneXpert MTB/RIF assay represents a paradigm shift in the diagnosis of TB and MDR-TB by simultaneous detection of M.tuberculosis and rifampicin resistance bacilli. However information regarding the performance characteristics of Xpert MTB/RIF assay is scarce in Ethiopia. Objective: To evaluate the performance of Xpert MTB/RIF assay for diagnosis of pulmonary tuberculosis and detection of Rifampicin resistance in sputum specimens at Karamara hospital, Jigjiga. Materials and methods: A total of 227 paired expectorated sputum samples from patients with signs and symptoms of suggestive of tuberculosis at Karamara hospital during February 2014 to May 2014 were recruited by consecutive sampling method. Sputum sample was tested directly by Ziehl-Neelsen staining and Xpert MTB/RIF assay without NALC-NaOH decontamination and sputum samples were cultured for isolation and drug sensitivity testing of TB bacilli. Diagnostic performance of Xpert MTB/RIF assay and AFB smear microscopy was calculated using sensitivity, specificity, positive and negative predictive values, positive and negative likelihood ratios against culture as the gold standard. Results with contaminated cultures (for both LJ and MGIT) and failed Xpert MTB/RIF were excluded from analysis. Results: Overall 25.5% (58/227) samples were positive for MTBC by MGIT and/or LJ media of which 36.2 % (21/58) and 65.5% (35/58) were positive by AFB smear microscopy and Xpert MTB/RIF respectively. The sensitivity, specificity, positive and negative predictive value of Xpert MTB/RIF assay were 65.5% (95% CI: 53.3-77.7%), 96.3% (95% CI: 93.4-99.2%), 86.4% (95% CI: 76.2-96.5%), and 88.6% (95% CI: 83.9-93.3%) respectively. Eighteen (31.0%, 18/58) more cases, which were smear microscopy negative, were detected by Xpert MTB/RIF assay Conclusion: Xpert MTB/RIF assay demonstrated high sensitivity in detecting MTBC in sputum specimens compared with conventional AFB smear microscopy. However, it demonstrated suboptimal sensitivity in smear negative patients compared to culture test. Keywords: Xpert MTB/RIF assay, NPV, PPV, Sensitivity, SpecificityenXpert MTB/RIF assayNPV, PPVSensitivity, SpecificityThesis