Evaluation of GeneXpert and liquid culture for detection of Mycobacterium tuberculosis in pediatric patients

Indian J Med Microbiol. 2022 Oct-Dec;40(4):547-551. doi: 10.1016/j.ijmmb.2022.07.010. Epub 2022 Aug 18.

Abstract

Purpose: Evaluation of GeneXpert in comparison to liquid culture using Mycobacteria Growth Indicator Tube (MGIT) as gold standard for detection of Mycobacterium tuberculosis (MTB) in children.

Methods: A total of 8123 samples, both pulmonary (5830) and extra pulmonary (2293) received from pediatric patients were processed for Acid Fast Bacilli (AFB) smear, GeneXpert and MGIT culture simultaneously.

Results: Out of 8123 samples, 493 (6.1%) samples were found positive by GeneXpert and 508 (6.2%) samples by MGIT culture, 371 (4.6%) were found positive by both GeneXpert and MGIT culture. MGIT detected 137 (1.7%) extra positive than GeneXpert while GeneXpert detected 122 (1.5%) extra samples more positive than by MGIT. Sensitivity of GeneXpert was 73% and concordance between both methods was 96.8%. Rifampicin resistance was found in 49 (9.9%) samples among MTB positive by GeneXpert. Turnaround time for GeneXpert was approx. 2 ​h and for MGIT, it was 12-28 days.

Conclusion: Good sensitivity (73%) and concordance (96.8%) were observed for GeneXpert against MGIT culture in this study. GeneXpert can simultaneously detect MTB and rifampicin resistance in less than 2 ​h while MGIT takes 12-28 days for MTB detection only.

Keywords: Extra pulmonary TB; MGIT; Pulmonary TB; Rifampicin resistance.

MeSH terms

  • Child
  • Humans
  • Mycobacterium tuberculosis* / genetics
  • Rifampin / pharmacology
  • Sensitivity and Specificity
  • Sputum / microbiology

Substances

  • Rifampin