Dependence of Xpert MTB/RIF Accuracy for Detecting Rifampin Resistance in Bronchoalveolar Lavage Fluid on Bacterial Load: A Retrospective Study in Beijing, China

作者：Qin Lin, Fengmin Huo, Weicong Ren, Yuanyuan Shang, Cong Yao, Xuxia Zhang, Rongmei Liu, Liping Ma, Mengqiu Gao, Yu Pang · 发表于：Infection and Drug Resistance · 年份：2021 · DOI：10.2147/idr.s307488 · 被引用次数：15 · 研究领域：Tuberculosis Research and Epidemiology、Mycobacterium research and diagnosis、Pneumocystis jirovecii pneumonia detection and treatment

Introduction: We assessed the effect of Mycobacterium tuberculosis (MTB) bacterial load on Xpert MTB/RIF accuracy for detection of rifampicin (RIF)-resistant MTB in bronchoalveolar lavage fluid (BALF) specimens obtained at a national tuberculosis (TB) specialized hospital in Beijing, China. Methods: A retrospective study was conducted at Beijing Chest Hospital. Patients with symptoms suggestive of pulmonary TB who provided BALF specimens for routine MTB detection between June 2019 and July 2020 were enrolled in the study. Chi-square test and Student’s t -test were used to compare results across groups stratified according to BALF bacterial load. Results: In total, 1125 patients with positive Xpert results who were enrolled in final analysis, 263 provided BALF specimens that tested positive for RIF-resistant MTB via Xpert MTB/RIF. The RIF-resistance rate of specimens with very low MTB bacterial load was 30.9%, a resistance rate significantly greater than rates obtained for groups with high (25.0%), medium (17.3%) and low (19.2%) MTB loads ( P < 0.01). Notably, false-positive results obtained for the very low bacterial load group led to markedly reduced positive predictive value of Xpert MTB/RIF to provide correct RIF-resistance predictions for that group (67.1%, 95% CI: 56.1%– 78.1%5) relative to the predictive value obtained for all other groups combined (about 90%, P < 0.05). Sanger sequencing data obtained for 20 (32.8%) MTB isolates deemed RIF-resistant via Xpert (Probe E)...