Role of line probe assay in detection of Mycobacterium tuberculosis in children with pulmonary tuberculosis

Abstract

BackgroundIndia is the highest TB burden country in the world with almost 27 lakh cases reported in 2019. Pediatric tuberculosis in India accounts for almost 31% of global TB burden. Despite such high mortality and morbidity in children, diagnosis of pulmonary TB in children still remains very challenging. Material and methodsThis cross-sectional study was conducted in a tertiary care hospital in Delhi, India. Children between 1 and 12 months with clinical suspicion of pulmonary tuberculosis who had not previously taken ATT were included.Early morning gastric aspirate samples were collected after overnight fasting, on two days. Both days sputum sample were subjected to sputum smear microscopy and one of the two samples was subjected to line probe assay (LPA), cartridge based nucleic acid amplification (CBNAAT) and mycobacterium growth in tube (MGIT-960). Results84 children with pulmonary tuberculosis were enrolled. The most common presenting complaint was fever seen in 83 patients (98.8%). Only 17 (20.24%) were sputum smear positive by Ziehl- Neelsen (ZN) staining. LPA was positive in 47 (55.95%) samples and among these positive samples both INH and RIF resistance was detected in 2 (4.26%) samples. CBNAAT was positive in 53 patients (63%). Growth in liquid culture media (MGIT 960) was observed in 44 (52.38%) samples. Among 17 smear positive samples, LPA was detected in 14 (82.35%) samples and among 67 smear negative sample LPA was detected in 33 (49.25%) samples. LPA had 63.46% sensitivity, 100% specificity in detecting mycobacterium tuberculosis. DiscussionWHO's recommendation for using LPAs has been limited to culture isolates or smear-positive sputum specimens. New data has since been generated on the use of LPAs as newer versions of LPA have been developed over past few years.Previous studies conducted using LPA version 1.0 reported much lower detection rate of mycobacterium tuberculosis in smear negative specimens.With the availability of newer versions such as Hain GenoTypeMTBDRplusversion 2 and Nipro NTM + MDRTB detection kit 2, the diagnostic utility of LPA may be enhanced.