GeneXpert MTB/RIF on bronchoalveolar lavage samples in children with suspected complicated intrathoracic tuberculosis: a pilot study.

Background: Children with complicated intrathoracic tuberculosis (TB) require rapid confirmation of TB diagnosis and of drug susceptibility to institute appropriate therapy. In a pilot study, we evaluated the feasibility and potential utility of GeneXpert (Xpert) on bronchoalveolar lavage (BAL) samples in children undergoing routine diagnostic bronchoscopy.

Methods: We included children <13 years of age undergoing bronchoscopy for suspected complicated intrathoracic TB at Tygerberg Children's Hospital, October 1, 2012-May 15, 2013. A minimum of two respiratory specimens in addition to BAL were obtained from each child. In addition to fluorescent smear microscopy and automated liquid culture performed on all samples, BAL samples were analyzed by Xpert. Drug susceptibility was confirmed by GenoType(®) MTBDRplus.

Results: Fourteen children (2 HIV positive, median age 16 months) were included. The Mantoux tuberculin skin test was positive in 11. On chest radiograph, six children had expansile pneumonia and nine had airway compression (one had both). The median duration of TB treatment before bronchoscopy was 8 days. TB was confirmed by either culture or Xpert from any sample in 11 (78%) children. Among 9/14 (64%) cases confirmed by culture, BAL Xpert was positive in 7 (78% sensitivity); in addition, Xpert confirmed 2 cases who had negative culture (14% additional diagnostic yield). Two drug resistant cases were identified: one by BAL Xpert and one from genotypic testing of a culture from gastric aspirate. All children were initiated on anti-TB treatment and responded well to therapy.

Conclusion: BAL Xpert resulted in additional diagnostic yield and also in the rapid detection of drug resistance in children with complicated intrathoracic TB. The clinical impact of this modality should be further evaluated in children.