Evaluation of Xpert MTB/RIF testing for rapid diagnosis of childhood pulmonary tuberculosis in children by Xpert MTB/RIF testing of stool samples in a low resource setting

Abstract

ObjectiveChildren with tuberculosis (TB) remain underdiagnosed due to difficulty in testing for Mycobacterium tuberculosis (MTB) infection. We evaluated the Xpert MTB/RIF assay for respiratory and stool testing in children for pulmonary TB through a cross-sectional study at tertiary care facilities in Karachi, Pakistan. Fifty children aged 0–15 years screened by a modified Kenneth-Jones (KJ) score were included. Mycobacterial culture of respiratory samples was the microbiological standard against stool Xpert TB results. All positive TB cases were compared against a treatment response standard (TRS).ResultsTwelve study subjects were diagnosed by Xpert TB and nine by MTB culture. Compared with culture [gastric aspirates (GA)/sputum (spm)], stool Xpert TB had a sensitivity of 88.9% (95% CI 50.7–99.4) and a specificity of 95% (95% CI 81.8–99.1). Xpert TB stool versus GA/spm had sensitivity of 81.8% (95% CI 47.8–96.8) and specificity of 94.7% (95% CI 84.6–99.9). We found good agreement (kappa scores of >0.8) between stool Xpert, GA/spm Xpert and GA/spm culture. Stool Xpert PPV and NPV against TRS was 100 and 82.1% respectively. Stool Xpert TB is a relatively easy option for diagnosis for pulmonary childhood TB in a high burden low-resource setting.Electronic supplementary materialThe online version of this article (doi:10.1186/s13104-017-2806-3) contains supplementary material, which is available to authorized users.

Molecular Detection of Mycobacterium tuberculosis from Stools in Young Children by Use of a Novel Centrifugation-Free Processing Method

“…This is the first large study, since initial proof-of-concept ( 10 ), to evaluate the performance of a novel centrifugation-free processing method for stool specimens, to assess its use with the Xpert MTB/RIF assay on stool to diagnose TB in children. Compared to microbiological confirmation using respiratory specimens, this method demonstrated diagnostic accuracy similar to those of recently published studies in young children ( 7 , 8 , 15 ), while studies enrolling mainly older children reported higher sensitivities for stool Xpert ( 9 , 16 , 17 ). This is most likely due to the lower bacillary concentrations present in respiratory specimens and, hence, in stools of young children, who seldom present with adult-type (cavitating) TB ( 18 , 19 ).…”

Comparison of GeneXpert MTB to Mycobacterium tuberculosis culture in children with tuberculosis

“…Tang et al showed a Kappa value of 0.73, in their study of both adults and children. 18 Hasan et al showed very good agreement (Kappa values >0.8), but with stool specimens, 19 and Li et al showed a Kappa value of 0.6 for extrapulmonary TB. 20 We assessed what factors were associated with GeneXpert MTB test in predicting which children were likely to have positive results.…”

“…6 Statistical guidance on reporting results from studies evaluating diagnostic tests was used to calculate sensitivity and specificity of the assay and value of agreement with Kappa scores. 9 Sekadde et al in Uganda described clinical characteristics associated with a positive Xpert MTB test. The clinical characteristics which were independently associated with a positive Xpert MTB test included age > 5 years, a positive history of TB contact, and a positive tuberculin test.…”

Which sample type is better for Xpert MTB/RIF to diagnose adult and pediatric pulmonary tuberculosis?

“…We identified 50 articles: 17 [7,[24][25][26][27][28][29][30][31][32][33][34][35][36][37][38][39] in the adult BAL group, 14 [35,[40][41][42][43][44][45][46][47][48][49][50][51][52] in the adult ES group, 7 [35,45,50,[53][54][55][56] in the adult IS group, 2 [57,58] in the pediatric ES group, 6 [57,[59][60][61][62][63] in the pediatric GA group, and 9 [59,[64][65][66][67]…”