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