The use of GeneXpert Mycobacterium tuberculosis/rifampicin assay in diagnosis of pulmonary tuberculosis in children

Abstract

Introduction Rapid diagno sis of tuberculosis (TB) is essential for early disease management. GeneXpert (GX) test is a novel rapid diagnostic modality. In this study, we aimed to evaluate the diagnostic role of GX test in diagnosing pulmonary tuberculosis (PTB) in children as well as detection of rifampicin (RIF) resistance. Patients and methods This was a cross-sectional study that included 80 patients suspected to have PTB based on clinical data together with at least one of the followings: a positive tuberculin skin test or QuantiFERON-TB Gold In-Tube test result, a positive blood TB PCR result, or a positive Ziehl–Neelsen staining result. Results PTB was more common in older females. Extrapulmonary manifestations and hilar lymphadenopathy were more frequent in younger age. Both positive tuberculin skin test and positive GX were more frequent in older age. Positive GX was found in 30 (37.5%) cases, and RIF resistance was detected in two (6.6%) of them. Positive GX results were more frequent in sputum than gastric aspirate samples. Positive GX results were more frequent with absent Bacillus Calmette–Guerin scar, and with hemoptysis, failure to thrive, cavitary lung lesions, and lower mean hemoglobin. Conclusion GX detects many more cases than blood PCR and Ziehl–Neelsen stain. GX had 70% sensitivity and 95% specificity in diagnosing PTB, with overall diagnostic accuracy of 86.67%, with better performance in older children who could expectorate. RIF resistance was ∼6.6%.