Use Of Xpert For The Diagnosis Of Pulmonary Tuberculosis In Severely Malnourished Hospitalized Malawian Children

Abstract

Background Pulmonary tuberculosis contributes to increased morbidity and mortality in severely malnourished children in endemic settings. Despite high clinical suspicion, few tuberculosis prevalence estimates exist in malnourished African children. Diagnostics such as Xpert MTB/RIF may help to determine pulmonary tuberculosis prevalence, however its performance in severely malnourished children is largely unknown. Methods We conducted a cross-sectional observational study evaluating Xpert compared to smear microscopy and liquid culture on induced sputums among severely malnourished children (aged 6 to 60 months) at Kamuzu Central Hospital in Lilongwe, Malawi. From February 1 to May 30, 2012, children who met World Health Organization 2006 guidelines for severe acute malnutrition were evaluated using clinical symptoms, tuberculin skin tests, chest radiographs, and induced sputums. National Institute of Health (NIH) consensus case definitions were used to estimate tuberculosis prevalence. Results Three hundred severely malnourished children (median age 18.5 months, IQR 12.1-25.6) had one induced sputum performed; 295 (98.3%) received two. Fifty-two (17.6%) were HIV-infected. Over 25% had tuberculosis exposure with 48/297 (16.2%) reporting contact and 40/287 (13.9%) with positive TST. Two (0.7%) patients had confirmed tuberculosis by Xpert and culture, but only one had positive smear microscopy. Twenty (6.7%) patients fulfilled probable and 97 (66%) met possible tuberculosis NIH case definitions. Overall mortality was 9.7%. Conclusions Microbiologic confirmation likely underestimates the prevalence of pulmonary tuberculosis in severely malnourished children. In our study, Xpert on induced sputums did not increase case finding. Future studies are needed using Xpert among targeted groups of severely malnourished children and on non-sputum specimens.

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%.…”

Xpert MTB/RIF assay for the diagnosis of pulmonary tuberculosis in children: A systematic review and meta-analysis

“…We selected 15 studies for inclusion (figure 1). [12][13][14][15][16][17][18][19][20][21][22][23][24][25] Five studies were done in low-income countries, two in lower middle-income, six in upper middle-income, and two in high-income countries (table 1). 26 12 studies were done at tertiary, university, or research facilities.…”

Childhood Tuberculosis

“…On the other hand, it is expensive; needs calibration, maintenance, and linkage to a computer and secured premises; needs continuous electrical power supply and air conditioning; cannot differentiate between live and dead Mtb; and thus, cannot be used to monitor treatment success, failure, or relapse [15]. Use of Xpert MTB/RIF was not supported in a study done in malnourished children from a high TB area in Malawi [64].…”