The value of lateral flow urine lipoarabinomannan assay and empirical treatment in Xpert MTB/RIF ultra negative patients with presumptive TB: a prospective cohort study

Abstract

The value of Lateral Flow urine Lipoarabinomannan (LF-LAM) assay and the role of empiric tuberculosis (TB) treatment in the era of the highly sensitive Xpert MTB/RIF Ultra (Xpert Ultra) assay is unclear. This study aimed to assess the additional yield of LF-LAM assay when used in combination with Xpert Ultra, and the role of empiric TB treatment when Xpert Ultra used as the initial diagnostic in presumptive TB cases admitted to a tertiary hospital in Ethiopia. We performed a secondary analysis of a cohort of hospitalized Xpert MTB/RIF-negative patients. Sputum samples were examined for Mycobacterium tuberculosis by culture and Xpert Ultra. In HIV positive and severely ill patients, a urine sample was collected for the LF-LAM assay. Treatment outcome was assessed six months after enrollment. Logistic regression was used to identify factors predictive of deaths among Xpert Ultra negative patients. The Xpert Ultra assay diagnosed 31 of the 35 culture positive among the 250 hospitalized Xpert MTB/RIF-negative participants. The LF-LAM assay did not identify any case not detected by Xpert Ultra among the 52 (21.4%) participants living with HIV and the 16 patients with severe disease. Among Xpert Ultra negative patients, those who received empirical TB treatment had a similar odds of death (aOR 0.74, 95% CI: 0.1–2.7) as those not started on TB treatment. Low body mass index (≤ 18.5 kg/m2) was the only significant predictor of death in Xpert Ultra negative patients (aOR 4. 0, 95% CI: 1.08–14.6). In this prospective cohort, LF-LAM did not improve the diagnostic yield when used in combination with Xpert Ultra. Empiric TB treatment for Xpert Ultra negative presumptive TB cases was not associated with death at six months. Future studies in diverse settings should be to determine the optimal management of Xpert Ultra negative patients.

Subacute Cardiac Tamponade Due to Tuberculous Pericarditis Diagnosed by Urine Lipoarabinomannan Assay in a Immunocompetent Patient in Oyam District, Uganda: A Case Report

“…However, this method has some limitations such as a shelf life of the test of about 3 months and the presence of the matrix components due to the different composition of human urine that may mask and/or change the conformation of either antibodies or LAM epitopes in the assay, as well as the type of assay used [ 25 ]. The urine TB-LAM test is performed by applying 60 μL of fresh urine to the sample using a micro-pipette [ 26 ], there is a lack of information in the literature about the use of LF-LAM in end-stage renal disease. The use of serum antilipoarabinomannan (anti-LAM) antibody detection for the diagnosis of latent TB in a dialysis population has been evaluated in association with the tuberculin skin test [ 27 ].…”

Bacterial pathogens in Xpert MTB/RIF Ultra-negative sputum samples of patients with presumptive tuberculosis in a high TB burden setting: a 16S rRNA analysis

“…In 2017, the World Health Organization (WHO) endorsed the Xpert Ultra assay ( 17 ) given its excellent performance for the diagnosis of TB, with a pooled sensitivity of 88% (95% CI: 85% to 91%) and specificity of 96% (95% CI: 94% to 97%) compared to liquid culture ( 18 , 19 ). With a high negative predictive value (98.1%), patients presenting with symptoms of TB whose sputum sample is Xpert Ultra negative are thus highly unlikely to suffer from pulmonary TB ( 20 ). This raises the question whether empiric TB treatment for patients with negative Xpert Ultra test results is the correct management.…”