Rapid Diagnosis of Childhood Pulmonary Tuberculosis by Xpert MTB/RIF Assay Using Bronchoalveolar Lavage Fluid

Abstract

In order to evaluate the diagnostic accuracy of the Xpert MTB/RIF assay on childhood pulmonary tuberculosis (PTB) using bronchoalveolar lavage fluid (BALF), we evaluated the sensitivity, specificity, positive predictive value, and negative predictive value of Xpert MTB/RIF assay using BALF in comparison with acid-fast bacilli (AFB) microscopy and Mycobacterium tuberculosis (MTB) culture for diagnosing childhood PTB using Chinese “composite clinical reference standard” (CCRS) as reference standard. Two hundred fifty-five children with suspected PTB were enrolled at Beijing Children's Hospital from September 2010 to July 2013. Compared with Chinese CCRS, the sensitivity of AFB microscopy, MTB culture, and Xpert MTB/RIF assay was 8.4%, 28.9%, and 53.0%, respectively. The specificity of three assays was all 100%. Xpert MTB/RIF assay could detect 33.9% of cases with negative MTB culture, and 48.7% of cases with negative AFB microscopy. Younger age (<3 years), absence of BCG scar, and contact with TB patient were found significantly associated with a positive result of Xpert MTB/RIF assay. In conclusion, Xpert MTB/RIF assay using BALF can assist in diagnosing childhood PTB much faster when fiberoptic bronchoscopy is necessary according to the chest radiograph.

Comparison of GeneXpert MTB/RIF Assay in Broncho Alveolar Lavage and Gastric Lavage Samples

“…In a comparative study performed by QQ Yin et al in 250 Chinese children of suspected TB showed Sensitivity of AFB microscopy, MTB culture, and GeneXpert MTB/RIF assay was 8.4%, 28.9%, and 53.0%, respectively. GeneXpert MTB/RIF assay could detect 33.9% of cases with negative MTB culture, and 48.7% of cases with negative AFB microscopy [18]. In a prospective study on children by Brown et al showed culture of gastric lavage had sensitivity only 30% and induced sputum 39% [6].…”

Childhood Tuberculosis

“…[50] has concluded that this test will not be a crucial diagnostic tool in high burden countries, the WHO endorsed its use in children in 2013. Several studies published on its use in the pediatric population have shown promising results be it in gastric lavage [51,52], sputum [53][54][55][56][57][58][59], bronchoalveolar lavage specimens [60], or stool in HIV-infected patients [61].…”

What steps do we need to take to improve diagnosis of tuberculosis in children?

“…Nineteen studies are available on the use of Xpert MTB/RIF in the pediatric population [64,[69][70][71][72][73][74][75][76][77][78][79][80][81][82][83][84][85][86]. Overall, the sensitivity of this test in respiratory samples compared to culture for TB detection ranged between 39 and 100%, and in particular for sputum varied from 57 to 100%, for gastric lavage/aspiration from 64 to 80% and for nasopharyngeal aspirate from 39 to 65%.…”

“…Overall, the sensitivity of this test in respiratory samples compared to culture for TB detection ranged between 39 and 100%, and in particular for sputum varied from 57 to 100%, for gastric lavage/aspiration from 64 to 80% and for nasopharyngeal aspirate from 39 to 65%. Specificity, for all respiratory specimens varied from 70 to 100% [64,[69][70][71][72][73][74][75][76][77][78][79][80][81][82][83][84][85] (TABLE 3). A recent meta-analysis proved that Xpert MTB/RIF provides an excellent sensitivity in smear positive children for both gastric lavage/aspirate and expectorated/induced sputum (95%, 95% CI: 83-99 and 96%, 95% CI: 90-99, respectively) and an acceptable sensitivity for both sample types in smear-negative culture-positive children (62%, 95% CI: 44-80 and 55%, 95% CI: 41-69, respectively) [68].…”

“…Specificity and sensitivity of the Xpert MTB/RIF assay versus culture in different samples [64,[69][70][71][72][73][74][75][76][77][78][79][80][82][83][84][85] (cont.). n/a n/a [73] Biopsy (n n/a n/a n/a [77] Reither et al n/a n/a n/a [83] Nhu et al What steps do we need to take to improve diagnosis of tuberculosis in children? adults showed a pooled ability in detecting rifampicin resistance of 98.4% whereas of 88.7% in detecting isoniazid resistance [90].…”