Evaluation of the Xpert MTB/RIF assay in gastric lavage aspirates for diagnosis of smear-negative childhood pulmonary tuberculosis.

BACKGROUND: The diagnosis of pulmonary tuberculosis (TB) in children presents problems worldwide. The Xpert MTB/RIF assay serves as a useful alternative for the rapid diagnosis of childhood TB, with various clinical specimens.

METHODS: In this study, we evaluated the Xpert for diagnosis of smear-negative childhood pulmonary TB using gastric lavage aspirates (GLA). A total of 211 eligible children with suspected TB were consecutively recruited and had GLA obtained for analysis between October 2012 and October 2013 in Beijing Children's Hospital.

RESULTS: The percentages of TB children in <1 year [Odds ratio (95% confidence interval): 4.66 (1.81-11.97)], >5 years group [2.59 (1.30-5.16)] and of living in a rural region [3.78 (2.02-7.08)] were significantly higher than in control groups. The sensitivity in detecting children with a clinical diagnosis of TB for MGIT and Xpert was 12.1% (95% confidence interval: 9.3-14.9%) and 48.6% (95% confidence interval: 44.4-52.8%), respectively. The statistical analysis revealed that GeneXpert showed significantly better sensitivity than MGIT technology (P < 0.001).

CONCLUSIONS: We conclude that Xpert MTB/RIF assay is an excellent tool for the diagnosis of smear-negative childhood with GLA samples. The high proportion of very low mycobacterial load in the GLA samples from smear-negative TB cases may increase the frequency for obtaining indeterminate RIF resistance results by Xpert. In addition, the age <1 year, >5 years and living in a rural region are all high risk factors for childhood TB cases in China.