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
College of Health Sciences, Makerere University Lung Institute, Kampala, Uganda.
Mycobacteriology (BSL-3) Laboratory, Department of Medical Microbiology, Makerere University, Kampala, Uganda.
Open Forum Infect Dis. 2021 Apr 2;8(6):ofab173. doi: 10.1093/ofid/ofab173. eCollection 2021 Jun.
The Global Laboratory Initiative (GLI) guidelines recommend repeat for GeneXpertMTB/RIF (XpertMTB/RIF) in patients with a low pretest probability of rifampicin resistance (RR).
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 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).
A total of 126/130 patients had repeat XpertMTB/RIF results, of whom 97 (77.0%) had 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; = .01; aOR, 0.02; 95% CI, 0.01-0.35; = .01, respectively).
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.
全球实验室倡议（GLI）指南建议，对于利福平耐药（RR）预测试概率较低的患者，应重复进行GeneXpert MTB/RIF（Xpert MTB/RIF）检测。
这是一项横断面研究，使用了从参与STREAM 2试验筛查的参与者中收集的痰标本结果。我们招募了2017年9月至2019年10月期间在坎帕拉穆拉戈国家转诊医院被转诊开始接受RR/耐多药（MDR）结核病治疗的所有检测出Xpert MTB/RIF RR-TB的患者。在基线时，对痰标本进行涂片显微镜检查、重复Xpert MTB/RIF检测、Xpert Ultra检测和MTBDR检测。对结果不一致的标本进行基于培养的药敏试验（DST）。我们分析了初始和重复Xpert MTB/RIF RR结果不一致以及Xpert MTB/RIF RR假阳性的患病率和相关因素。Xpert MTB/RIF RR假阳性定义为Xpert Ultra、线性探针分析（LPA）或培养DST（参考对照）均未检测到RR。
130例患者中有126例获得了重复Xpert MTB/RIF检测结果，其中97例（77.0%）检测到RR，81例（83.5%）检测到RR，1例（1.0%）RR结果不确定。Xpert MTB/RIF RR结果不一致的患病率为15/96（15.6%），而Xpert MTB/RIF RR假阳性患病率为10/96（10.4%）。低菌量痰标本更有可能出现Xpert MTB/RIF RR结果不一致和Xpert MTB/RIF RR假阳性结果（校正比值比[aOR]分别为0.04；95%置信区间[CI]，0.00 - 0.37；P = 0.01；aOR为0.02；95% CI，0.01 - 0.35；P = 0.01）。
我们的研究结果显示，在结核病负担较低的患者中，利福平耐药的假阳性率较高，这就需要进行重复检测，以防止不必要地开具抗MDR-TB治疗药物。
