Performance Evaluation of the Abbott RealTime MTB and RIF/INH Resistance Assays for the Detection of Mycobacterium tuberculosis and Resistance Markers in Respiratory Specimens at Nigist Eleni Mohammed Memorial Hospital, Hosanna, South Ethiopia.

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Addis Ababa Universty


Background: Despite the availability of highly efficacious treatment, TB remains a major global health concern and its control is hampered by lack of early and accurate diagnosis. The Abbott RealTime MTB and RIF/INH assays are recently launched high-throughput automated nucleic acid amplification tests by Abbott laboratories for the rapid detection of Mycobacterium tuberculosis complex (MTB) and genetic markers of resistance to Isoniazid (INH) and Rifampin (RIF) from respiratory specimens. This test could be useful in Ethiopia for early and accurate diagnosis, however as far as our knowledge its performance is not evaluated so far. Objective: To evaluate the diagnostic performance of the Abbott RealTime MTB and RIF/INH assays for the detection of M. tuberculosis and resistance markers from respiratory specimens. Methods: A cross sectional study was conducted on 112 study subjects presumptive to have pulmonary tuberculosis at Nigist Eleni Mohammed Memorial Hospital, Hossana, South Ethiopia from April to December 2017. Two morning expectorated sputum specimens were collected from each study participant. One sample was tested directly by Xpert MTB/RIF assay and the other was used for smear microscopy, TB culture, Abbott RealTime MTB and INH/RIF Assays. Data was entered and analyzed using STATA statistical software version 12.1. Sensitivity, specificity, PPV and NPV was calculated using MGIT 960 as a reference. Kappa statistics was applied to test agreement between assays. Results: For the detection of MTB the Abbott RealTime MTB assay exhibited an overall sensitivity, specificity, PPV and NPV of 92.3%, 93.8%, 85.7% and 96.8% respectively. For Rifampicin resistance MTB (RR-MTB) detection, the Abbott RealTime MTB RIF/INH assay showed 100% sensitivity, specificity, PPV and NPV while for the detection of INH resistance MTB the sensitivity, specificity, PPV and NPV of the Abbott MTB RIF/INH assay was 81.8%, 100%, 91% and 100% respectively. In this study strong agreement was found between the Abbott RealTime MTB and Xpert/ RIF assays for MTB (k=0.81) and RR-TB detection (k= 1). Conclusion: The Abbott RealTime MTB and RIF/INH assays revealed high sensitivity and specificity in MTB diagnosis and provide reliable INH and RIF resistance profile. This test has similar diagnostic performance to Xpert RIF/INH assay with the advantages of high-throughput. This test could be a suitable and an alternative for high TB burden countries such as Ethiopia.



Abbott RealTime MTB, Abbott RealTime MTB RIF/INH, Performance