Xpert Mycobacterium tuberculosis/Rifampicin–Detected Rifampicin Resistance is a Suboptimal Surrogate for Multidrug-resistant Tuberculosis in Eastern Democratic Republic of the Congo: Diagnostic and Clinical Implications. (26th June 2020)

• Record Type: Journal Article
• Authors: Bisimwa, Bertin C; Nachega, Jean B; Warren, Robin M; Theron, Grant; Metcalfe, John Z; Shah, Maunank; Diacon, Andreas H; Sam-Agudu, Nadia A; Yotebieng, Marcel; Bulabula, André N H; Katoto, Patrick D M C; Chirambiza, Jean-Paul; Nyota, Rosette; Birembano, Freddy M; Musafiri, Eric M; Byadunia, Sifa; Bahizire, Esto; Kaswa, Michel K; Callens, Steven; Kashongwe, Zacharie M
• Is Part Of: Clinical infectious diseases. Volume 73:Number 2(2021)
• Page Start: e362
• Page End: e370
• Publication Date: 2020-06-26
• Subjects: GenoType MTBDRplus assay -- drug resistance -- rpoB mutations -- inhA mutations -- DRC; Communicable diseases -- Periodicals; 616.905
• DOI: 10.1093/cid/ciaa873
• Languages: English
• ISSNs: 1058-4838

Abstract

Abstract: Background: Rifampicin (RIF) resistance is highly correlated with isoniazid (INH) resistance and used as proxy for multidrug-resistant tuberculosis (MDR-TB). Using MTBDR plus as a comparator, we evaluated the predictive value of Xpert MTB/RIF (Xpert)–detected RIF resistance for MDR-TB in eastern Democratic Republic of the Congo (DRC). Methods: We conducted a cross-sectional study involving data from new or retreatment pulmonary adult TB cases evaluated between July 2013 and December 2016. Separate, paired sputa for smear microscopy and MTBDR plus were collected. Xpert testing was performed subject to the availability of Xpert cartridges on sample remnants after microscopy. Results: Among 353 patients, 193 (54.7%) were previously treated and 224 (63.5%) were MTBDR plus TB positive. Of the 224, 43 (19.2%) were RIF monoresistant, 11 (4.9%) were INH monoresistant, 53 (23.7%) had MDR-TB, and 117 (52.2%) were RIF and INH susceptible. Overall, among the 96 samples detected by MTBDR plus as RIF resistant, 53 (55.2%) had MDR-TB. Xpert testing was performed in 179 (50.7%) specimens; among these, 163 (91.1%) were TB positive and 73 (44.8%) RIF resistant. Only 45/73 (61.6%) Xpert-identified RIF-resistant isolates had concomitant MTBDR plus -detected INH resistance. Xpert had a sensitivity of 100.0% (95% CI, 92.1–100.0) for detecting RIF resistance but a positive-predictive value of only 61.6% (95% CI, 49.5–72.8) for MDR-TB. The most frequent mutations associated with RIF and INH resistance were S531L and S315T1, respectively. Conclusions: In this high-risk MDR-TB study population, Xpert had low positive-predictive value for the presence of MDR-TB. Comprehensive resistance testing for both INH and RIF should be performed in this setting. Abstract : Compared with MTBDR plus, Xpert MTB/RIF–identified rifampicin resistance had only 61.6% positive-predictive value for the presence of MDR-TB among adult patients in eastern Democratic Republic of Congo. Comprehensive isoniazid and rifampicin susceptibility testing are needed in this setting.