Lipoarabinomannan Antigen Assay (TB-LAM) for Diagnosing Pulmonary Tuberculosis in Children with Severe Acute Malnutrition in Mozambique

Background: Tuberculosis (TB) and malnutrition are important causes of morbidity and mortality in children in the developing world.

Aims: To assess the prevalence of pulmonary TB in severely malnourished children and evaluate TB detection using the urine lipoarabinomannan antigen assay (TB-LAM).

Methods: A retrospective analysis was conducted in all pediatric inpatients with severe acute malnutrition at a rural health center in Mozambique, from February to August 2018. All children underwent a physical examination and chest X-ray, and their nasopharyngeal aspirates and stool specimens were studied for mycobacterial culture and subjected to the Xpert MTB/RIF assay. TB-LAM tests were performed on urine.

Results: Of 45 included cases, 17 (37.8%) were clinically diagnosed as pulmonary TB. None of these were detected by the Xpert MTB test; 4 (8.9%) nasopharyngeal aspirates were TB-culture positive. Seventeen patients (37.8%)-all clinically diagnosed with TB-tested positive on the TB-LAM, while 23 (51.1%) were negative. In 5 (11.1%), the urine LAM was not done.

Conclusion: Although our sample size was small, TB was diagnosed and treated in more than a third of included children. The urine TB-LAM test showed a perfect correlation with clinical diagnosis of childhood TB.

Lay Summary: Severe acute malnutrition makes children more vulnerable to tuberculosis (TB) infections, but it is difficult to detect TB in children because they cannot always cough up phlegm, which is used in diagnostic processes. This study aimed to find out how many severely malnourished children had TB in Gaza, Mozambique, and to test the accuracy of a less-used diagnostic test: the lipoarabinomannan assay (TB-LAM). Of the 45 severely malnourished children who were admitted to our hospital, 17 were diagnosed with TB by their doctor. The TB-LAM corroborated the clinical diagnosis in all cases, while the other tests (Xpert MTB/RIF assay) and cultures failed to detect most of them. Overall, more than a third of severely malnourished children had TB, and the TB-LAM test-a simple, point-of-care method-was a highly accurate way to diagnose them. While larger studies are needed to confirm these results, our findings suggest that the TB-LAM could vastly improve TB diagnosis in malnourished children.