Discordance of the Repeat GeneXpert MTB/RIF Test for Rifampicin Resistance Detection Among Patients Initiating MDR-TB Treatment in Uganda. (2nd April 2021)

• Record Type: Journal Article
• Authors: Ssengooba, Willy; de Dieu Iragena, Jean; Komakech, Kevin; Okello, Iginitius; Nalunjogi, Joanitah; Katagira, Winceslaus; Kimuli, Ivan; Adakun, Susan; Joloba, Moses L; Torrea, Gabriela; Kirenga, Bruce J
• Is Part Of: Open forum infectious diseases. Volume 8:Number 6(2021)
• Publication Date: 2021-04-02
• Subjects: detection -- Repeat -- RR/MDR-TB -- Xpert; Communicable diseases -- Periodicals; Medical microbiology -- Periodicals; Infection -- Periodicals; 616.9
• DOI: 10.1093/ofid/ofab173
• Languages: English
• ISSNs: 2328-8957

Abstract

Abstract: Background: The Global Laboratory Initiative (GLI) guidelines recommend repeat for GeneXpertMTB/RIF (XpertMTB/RIF) in patients with a low pretest probability of rifampicin resistance (RR). Methods: This was a cross-sectional study using results of sputum specimens collected from participants screened for the STREAM 2 trial. We recruited all patients with XpertMTB/RIF RR-TB detected who were referred for RR/multidrug-resistant (MDR) TB treatment initiation at Mulago National Referral Hospital, Kampala, between September 2017 and October 2019. At baseline, smear microscopy, repeat XpertMTB/RIF, Xpert Ultra, and MTBDR plus assays were done on sputum specimens. Culture-based drug susceptibility testing (DST) was performed on discordant specimens. We analyzed the prevalence and factors associated with discordance between initial and repeat XpertMTB/RIF RR and false XpertMTB/RIF RR. False XpertMTB/RIF RR was defined as no RR detected by any of Xpert Ultra, LPA, or culture DST (reference comparator). Results: A total of 126/130 patients had repeat XpertMTB/RIF results, of whom 97 (77.0%) had M. tuberculosis detected, 81 (83.5%) had RR detected, and 1 (1.0%) had RR indeterminate. The prevalence of discordant XpertMTB/RIF RR was 15/96 (15.6%), whereas false XpertMTB/RIF RR prevalence was 10/96 (10.4%). Low–bacillary load sputum specimens were more likely to have discordant XpertMTB/RIF RR and false XpertMTB/RIF RR results (adjusted odds ratio [aOR], 0.04; 95% CI, 0.00–0.37; P = .01; aOR, 0.02; 95% CI, 0.01–0.35; P = .01, respectively). Conclusions: Our findings show a high false-positive rifampicin resistance rate in low–TB burden patients, which calls for repeat testing in order to prevent unnecessary prescription of anti-MDR-TB therapy.