Role of GeneXpert in extrapulmonary tuberculosis

Background Tuberculosis (TB) commonly affects the lung (pulmonary TB). Extrapulmonary TB (EPTB) can involve many systems. Diagnosis is often difficult. EPTB may be misdiagnosed with many other inflammatory, granulomatous, and neoplastic disorders. GeneXpert mycobacterium tuberculosis /rifampicin is a valuable test in diagnosis of pulmonary TB. There is limited research about its diagnostic role in EPTB. Patients and methods The aim of this study was to assess the diagnostic value of GeneXpert in EPTB. Samples from EPTB cases were sent for standard mycobacterial culture and GeneXpert assay. The sensitivity and specificity of GeneXpert were calculated. Results A total of 100 patients were included. Overall, 61 cases were definitely diagnosed as EPTB, whereas 39 cases were negative according to culture. GeneXpert was positive in 40 cases, which represent 65.6% of EPTB cases, and negative in 21 (34.4%) cases. Sensitivity and specificity of GeneXpert was 65.6 and 97.4%, respectively. The positive predictive value and negative predictive value were 97.4 and 64.4%, respectively. Conclusion GeneXpert is a rapid, valuable tool in diagnosis of patients with EPTB. It is a highly specific test with fair sensitivity. A multicenter study with larger sample size is needed to evaluate the diagnostic role of GeneXpert in different sites of EPTB.