Rapid Molecular Detection of Extrapulmonary Tuberculosis by the Automated GeneXpert MTB/RIF System

Abstract

In total, 521 nonrespiratory specimens (91 urine, 30 gastric aspirate, 245 tissue, 113 pleural fluid, 19 cerebrospinal fluid [CSF], and 23 stool specimens) submitted to the German National Reference Laboratory for Mycobacteria (NRL) from May 2009 to August 2010 were comparatively investigated with the new molecular-based GeneXpert MTB/RIF (Xpert) assay system and conventional liquid and solid culture methods. Twenty (3.8%) of the 521 specimens gave no interpretable result. Whereas the sensitivity of the Xpert assay with tissue specimens was 69.0% (20 out of 29 culture-positive cases detected), 100% sensitivity was found with the urine and stool specimens. The combined sensitivity and specificity of the Xpert assay were calculated to be 77.3% and 98.2%, respectively.