Publication date: Mar 22, 2025
Xpert MTB/RIF Ultra (Ultra) aimed to improve the specificity in identifying rifampicin-resistant tuberculosis (RR-TB), compared to Xpert MTB/RIF. In a nationwide study in Rwanda, patients diagnosed with RR-TB by Ultra between December 2021 and January 2024 underwent repeat Ultra testing, complemented by rpoB gene sequencing and phenotypic drug-susceptibility testing (pDST), serving as reference tests. Of 129 patients initially diagnosed with RR-TB by Ultra, only 41 (32%) had concordant rifampicin results upon repeat Ultra testing. The remaining 88 patients (68%) had unconfirmed resistance on repeat Ultra. Reference testing was available for 40 (98%) of 41 confirmed cases, all verified as true RR-TB. Among 88 unconfirmed cases, reference testing was available for 61 (69%), with seven (11%) confirmed as true RR-TB, while 54 (89%) were found to have rifampicin-susceptible TB. Notably, 89% of 55 patients with very low bacillary loads on their initial Ultra had false RR-TB results, a significantly higher risk of false resistance compared to other bacillary load categories combined (risk ratio: 8. 20; 95% CI: 3. 56-18. 85; p
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| Concepts | Keywords |
|---|---|
| December | False-positive |
| Rwanda | Paucibacillary TB |
| Tuberculosis | TB case management |
Semantics
| Type | Source | Name |
|---|---|---|
| disease | IDO | susceptibility |
| drug | DRUGBANK | Rifampicin |
| pathway | KEGG | Tuberculosis |
| disease | MESH | tuberculosis |