Comparison of Xpert® MTB/RIF and Xpert® MTB/RIF Ultra in pediatric pulmonary tuberculosis diagnosis

The World Health Organization (WHO) recommends Xpert® MTB/RIF (Xpert) and its advanced version, Xpert® MTB/RIF Ultra (Xpert Ultra), as first-line diagnostic tests for detecting pulmonary tuberculosis (PTB) and rifampicin resistance in children suspected of having the disease. Respiratory specimens (gastric lavage/bronchoalveolar lavage/sputum/endotracheal aspirate) obtained from 116 children with presumptive PTB were simultaneously processed using liquid medium culture, Xpert assay, and Xpert Ultra assay. Among the specimens from 116 children, six were excluded due to culture contamination (n = 5) or error in Xpert Ultra results (n = 1). Among the remaining 110 specimens, 20 were positive by liquid culture. The former and latter, of the two comparator tests gave a sensitivity of 90% and 95%, respectively. The respective specificity was 93.3% and 88.9%. Xpert Ultra showed a statistically significant slightly higher sensitivity than Xpert. Xpert Ultra showed slightly higher sensitivity than Xpert, with a minimal loss in specificity, partly due to the inclusion of trace results, which help detect paucibacillary cases.