Citation Information :
Sood AK, Bajaj M, Kumar R, Kanga A. Utility of GeneXpert for Detection of Mycobacterium tuberculosis and Rifampicin Resistance in Pediatric Tuberculosis. Pediatr Inf Dis 2019; 1 (4):137-141.
Background: Childhood tuberculosis (TB) is an important cause of morbidity and mortality in the developing countries. In 2014, the World Health Organization (WHO) recommended the use of GeneXpert as the initial diagnostic test for detecting all cases of pediatric TB. Only limited data are available on the utility of GeneXpert in the diagnosis of pediatric TB. The present study was done to evaluate the efficacy of GeneXpert as diagnostic tool for pediatric TB detection. Objectives: To understand the utility of GeneXpert for detecting Mycobacterium tuberculosis and rifampicin resistance in pediatric TB. Materials and methods: This was a prospective cross-sectional study done in a tertiary care teaching hospital over a period of 1 year. After obtaining consent, sputum/induced sputum (IS)/gastric aspirate (GA)/fine needle aspiration cytology (FNAC)/cerebrospinal fluid (CSF)/pleural tap samples were obtained and subjected for cartridge-based nucleic acid amplification test (CBNAAT) and Mycobacterium growth indicator tube (MGIT) culture, respectively. Results: Based on the inclusion criteria, 128 children with presumptive TB were enrolled; of which 76 children were diagnosed with TB [30 with pulmonary TB (PTB) and 46 with extrapulmonary tuberculosis (EPTB)]. In EPTB, lymph node TB was most commonly seen in 37.0% subjects. In pulmonary TB, GeneXpert sensitivity and specificity were 85.71% (95% confidence interval, CI 62.64–96.23%) and 77.7% (95% CI 40.19–96.05%), respectively. Observed positive predictive value (PPV) and negative predictive value (NPV) of GeneXpert were 90% (95% CI 66.87–98.24%) and 70% (95% CI 35.36–91.90%), respectively. Sensitivity and specificity in EPTB was observed to be 50% (95% CI 28.80–71.19%) and 83.33% (95% CI 61.81–94.52%) with PPV of 73.33% (44.82–91.08%) and NPV of 64.51% (45.38–80.17%), with an overall sensitivity and specificity of GeneXpert of 67.39 and 92.68%, respectively, and PPV and NPV of 83.78 and 83.51, respectively. All the recruited subjects were found to be rifampicin sensitive. Conclusion: GeneXpert is a very useful test with a high sensitivity and specificity for diagnosing pediatric TB and for detection of rifampicin resistance in a short period of time.
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