Xpert(®) MTB/RIF assay for the diagnosis of pulmonary tuberculosis in children

Abstract

Setting: A tertiary care teaching hospital in New Delhi, India.

Objective: To determine the sensitivity and specificity of the Xpert(®) MTB/RIF assay in paediatric pulmonary tuberculosis (PTB) using MGIT™ culture as gold standard.

Methods: After ethical approval had been obtained, 50 patients aged 0-14 years with suspected PTB were enrolled. Sputum/induced sputum and gastric lavage from the participants were sent for direct smear, MGIT culture and Xpert testing. Chest X-ray and tuberculin skin test (TST) were also performed. PTB diagnosis was made without considering Xpert results according to the Revised National Tuberculosis Control Programme (RNTCP) algorithm. The sensitivity and specificity of Xpert were calculated using culture as gold standard.

Results: Of 50 individuals with suspected PTB, 23 (46%) were diagnosed with PTB based on the RNTCP algorithm. Sixteen children from the PTB group (69.5%) were Xpert-positive. None in the 'not PTB' group were Xpert-positive. With culture as gold standard, Xpert sensitivity and specificity were respectively 91.6% (95%CI 59.7-99.5) and 86.8% (95%CI 71.1-95.05).

Conclusion: In almost 70% of PTB cases, a definitive diagnosis could be made within 2 h using Xpert, establishing its role as a sensitive and specific point-of-care test.