Can sputum GeneXpert (Xpert MTB/RIF) be used in pediatric patients?

Use of Sputum GeneXpert in Pediatric Patients

Sputum GeneXpert (Xpert MTB/RIF) can be used in pediatric patients for tuberculosis diagnosis, though collection methods must be adapted to the child's age and ability to produce sputum. 1

Collection Methods for Pediatric Sputum Specimens

• For children who cannot expectorate sputum spontaneously, alternative collection methods include:

  • Gastric aspirates (after overnight fast) - yield of up to 40-50% in general, higher in infants (up to 90%) and children with extensive disease (up to 77%) 1
  • Sputum induction with bronchodilator - yield of 20-30% 1
  • Nasopharyngeal aspiration - yield of 20-30% 1
  • Bronchoalveolar lavage - yield of 10-22% 1

• Sputum induction has been demonstrated to be safe in young children with a low risk of side effects (epistaxis 19.4%, wheezing 1.1%) 2

Diagnostic Value in Children

• Mycobacterial culture of respiratory specimens is suggested for all children suspected of having pulmonary TB (conditional recommendation, moderate-quality evidence) 1

• GeneXpert MTB/RIF testing can replace sputum microscopy for initial diagnostic testing in children when available, especially in high TB prevalence settings 1

• In pediatric patients, GeneXpert has shown good sensitivity (73%) and concordance (96.8%) when compared to liquid culture (MGIT) 3

• The diagnostic yield is significantly affected by:

  • Age of the child (higher yield in infants and older children) 1
  • Extent of disease (higher yield in symptomatic children with extensive disease) 1
  • Quality of specimen collection (meticulous attention to detail during collection improves yield) 1

Practical Considerations

• Collection of specimens on 3 consecutive mornings provides the best diagnostic yield 1

• GeneXpert offers rapid results (approximately 2 hours) compared to culture methods (12-28 days), allowing for faster clinical decision-making 3

• GeneXpert simultaneously detects TB and rifampicin resistance, providing critical information for treatment planning 3, 4

• In settings with limited resources, a single pooled sputum specimen for GeneXpert may be considered as it has shown high negative predictive value (97.9%) 5

Important Caveats

• Microbiological confirmation is more challenging in children than adults due to the paucibacillary nature of pediatric TB 1

• In some circumstances, microbiological confirmation may not be necessary for children with uncomplicated pulmonary TB identified through a recent contact investigation if the source case has drug-susceptible TB 1

• When drug resistance is suspected or no source-case isolate is available, attempts to isolate organisms become critical for appropriate treatment selection 1

• For children at high risk of drug-resistant TB, GeneXpert assay should replace sputum microscopy, but sputum cultures, drug susceptibility testing, and chest radiographs should also be performed when feasible 1