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

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.

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.

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%.

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.