GeneXpert MTB/RIF and GeneXpert MTB/RIF ultra in tuberculosis diagnosis: A comparative evaluation

Abstract

Introduction: Recent studies have shown that Gene Xpert MTB/RIF (Xpert) and Gene Xpert MTB/RIF ultra (Xpert-U) tests outperform traditional microbiological methods in detecting tuberculosis (TB) and identifying rifampicin resistance. This research aimed to examine their diagnostic accuracy and clinical relevance. Materials and Methods: This retrospective cohort study included patients aged 18 years and older with pulmonary or extrapulmonary samples analyzed by Xpert, Xpert-U, and conventional diagnostic methods between January 2016 and June 2020. The diagnostic performance of Xpert and Xpert-U was compared across four patient groups: A) Microscopy-culture-positive pulmonary TB, B) Microscopy-negative, culture-positive pulmonary TB, C) Pulmonary TB cases, and D) Extrapulmonary TB cases. Results: A total of 1.366 samples (1.280 pulmonary, 86 extrapulmonary) were analyzed using Xpert and Xpert-U, including 1.042 males (76.3%) and 324 females (23.7%), with an average age of 54 years. For pulmonary TB, Xpert showed an overall sensitivity of 99.29% and specificity of 49.23%. Xpert-U demonstrated similar sensitivity at 98.56%, with an improved specificity of 89.66%. In extrapulmonary TB, Xpert-U achieved 100% sensitivity with a specificity of 70.59%. Conclusion: Xpert and Xpert-U tests offer high sensitivity for detecting Mycobacterium tuberculosis, greatly improving the timely diagnosis and management of TB, especially in cases with low bacterial loads or drug resistance.