Diagnostic accuracy of Xpert MTB/RIF ultra for detection of Mycobacterium tuberculosis in children: a prospective cohort study

The Xpert MTB/RIF Ultra is a recent advancement in molecular diagnostics of tuberculosis (TB) with higher sensitivity compared to its predecessor, the Xpert MTB/RIF assay. Prospective studies evaluating the performance of Xpert MTB/RIF Ultra in children with suspected TB are lacking. In this study, we evaluated the Xpert MTB/RIF Ultra for detection of Mycobacterium tuberculosis in samples from 156 children, of which one was excluded from the analysis. Of the remaining 155 samples, 6·5% (10/155), 21·3% (33/155), 20% (31/155) and 21·9% (34/155) were positive by smear examination, MGIT culture, Xpert MTB/RIF and Xpert MTB/RIF Ultra, respectively. The Xpert MTB/RIF and Xpert MTB/RIF Ultra had a similar overall sensitivity of 81·8% (95% CI: 64·5–93) and 84·8% (95% CI: 68·1–94·9), respectively. In suspected pediatric TB patients, the Xpert MTB/RIF Ultra had higher sensitivity compared to the Xpert MTB/RIF (72·7 vs 63·6). The AUC (area under the curve) of 0·905 for the Xpert MTB/RIF and 0·893 for the Xpert MTB/RIF Ultra indicate similar and good overall performance. Both Xpert assays were found to be equally efficient, however Xpert MTB/RIF Ultra showed better detection rate in suspected TB cases.