Accuracy of Xpert MTB/RIF Ultra for the diagnosis of tuberculosis in adult patients: a retrospective cohort study

Objectives: The value of the trace result in Xpert Ultra for diagnosing active tuberculosis (TB) remains unclear. Our study evaluated the diagnostic accuracy of Xpert MTB/RIF Ultra (Xpert Ultra) (Cepheid, Sunnyvale, USA) over Xpert MTB/RIF (Xpert) (Cepheid, Sunnyvale, USA) and mycobacterial culture when compared with a composite reference standard (CRS). Methods: A retrospective single-center observational study was conducted in a tertiary care hospital in South India. Over three months, patients (aged >= 15 years) data on Xpert Ultra tests and mycobacterial culture of pulmonary and extrapulmonary samples were extracted from their electronic medical records. Patients were defined as TB cases based on the CRS criteria. Sensitivity, specificity, positive and negative predictive values of diagnostic tests were calculated by comparing them to the CRS. Results: Xpert Ultra was more sensitive (87.8%) than Xpert (72.1%) and culture (44.1%). The specificity of Xpert Ultra was lower (98.1%) than those of Xpert (100%) and culture (10 0%). The sensitivity (92%) and specificity (100%) of Xpert Ultra were highest when performed on pus samples. Conclusions: Xpert Ultra with the trace category is superior to the conventional Xpert, and mycobacterial culture in identifying TB. (c) 2022 The Author(s). Published by Elsevier Ltd on behalf of International Society for Infectious Diseases. This is an open access article under the CC BY-NC-ND license ( http://creativecommons.org/licenses/by-nc-nd/4.0/ )

Automated summary

This study evaluated the diagnostic accuracy of Xpert Ultra for tuberculosis and found that it was more sensitive than conventional Xpert and mycobacterial culture. The sensitivity and specificity of Xpert Ultra were highest when performed on pus samples.