Multicentre evaluation of Xpert MTB/RIF assay in detecting urinary tract tuberculosis with urine samples

Genitourinary tuberculosis (GUTB) accounts for up to 40% of extrapulmonary tuberculosis cases. Rapid tests for GUTB are urgently needed because it is often associated with delayed health-care seeking, leading to serious consequences. This study evaluated the performance of the Xpert MTB/RIF assay in the rapid diagnosis of urinary tract tuberculosis (UTB) and rifampicin-resistant tuberculosis with urine specimens. In all, 302 patients were included from four hospitals in China. Suspected UTB patients were tested with Xpert, smear, and MGIT 960 culture. Drug susceptibility testing (DST) was conducted for culture-positive cases. The performance of the assays was evaluated against MGIT 960 culture and a composite reference standard (CRS). Among all participants, 150 (49.7%) had CRS-positive UTB, of whom 36 (24.0%) were culture-confirmed. Against culture, Xpert and smear achieved a sensitivity of 94.4% (95% CI: 81.3-99.3%) and 22.2% (95% CI: 10.1-39.2%), respectively. Against CRS, the sensitivity of Xpert, smear and culture was 41.3% (95% CI: 33.4-49.7%), 7.3% (95% CI: 3.7-12.7%), and 24.0% (95% CI: 17.4-31.6%). Xpert had better performance than smear and culture in detecting UTB from urine samples and could be considered for the diagnosis of UTB. Moreover, Xpert showed better performance than MGIT 960-based DST using urine culture.