Genexpert test and tuberculous pleural effusion: a new diagnostic method for an old medical problem

Abstract

Background There is no doubt about the diagnostic role of the GenXpert test in pulmonary tuberculosis (TB). Nevertheless, few data are available with regard to the use of this assay to test nonsputum clinical samples when investigating suspected extrapulmonary TB such as pleural effusion. Objective The aim of this study was to evaluate the accuracy of the GeneXpert test in the diagnosis of tuberculous pleural effusion (TPE). Patients and methods This cross-sectional analytic study was carried out at Assiut University Hospital in collaboration with Assiut Chest Hospital, Assiut, Egypt. The study included adults who had exudative pleural effusion of high-TB suspicion. For microbiological examination, one pleural fluid sample was treated and subjected to smear microscopy by Ziehl–Neelsen staining. Another sample was taken to be processed for GeneXpert MTB/RIF assay. For histopathological diagnosis, all studied patients were subjected to pleural biopsy, and the pleural histopathology was applied as a reference standard. Results GeneXpert had 26.7% sensitivity and 100% specificity in diagnosing TPE; the area under the curve was 0.63, and overall diagnostic accuracy was 59.3%. Conclusion We concluded that the GeneXpert test has poor sensitivity for the diagnosis of TPE. However, due to its high specificity, it can potentially avoid the need for unfair action in at least one-quarter of patients with TPE.