Determinants of PCR performance (Xpert MTB/RIF), including bacterial load and inhibition, for TB diagnosis using specimens from different body compartments

摘要: The determinants of Xpert MTB/RIF sensitivity, a widely used PCR test for the diagnosis tuberculosis (TB) are poorly understood. We compared culture time-to-positivity (TTP; surrogate bacterial load), TB-specific and internal positive control (IPC)-specific C(T) values, clinical characteristics in patients with suspected TB who provided expectorated (n = 438) or induced sputum 128), tracheal aspirates 71), bronchoalveolar lavage fluid 152), pleural 76), cerebral spinal (CSF; n pericardial 131), urine 173) specimens. Median load (TTP days) was strongest associate positivity each fluid. TTP correlated values pulmonary specimens but not extrapulmonary (Spearman's coefficient 0.5043 versus 0.1437; p 0.030). Inhibition affected greater proportion than (IPC > 34: 6% (47/731) 1% (4/381; < 0.0001). Pulmonary had [TTPs (interquartile range) 11 (7-16) 22 (18-33.5) days; 0.0001]. HIV-infection associated decreased likelihood MTB/RIF-positivity an increased Mycobacterial load, which displays significant variation across different body compartments, is main determinant rather inhibition. poor