Lipoarabinomannan In Serum Research Articles

Real-world diagnostic accuracy of lipoarabinomannan in three non-sputum biospecimens for pulmonary tuberculosis disease

Development of a non-sputum test using readily-obtainable biospecimens remains a global priority for tuberculosis (TB) control. We quantified lipoarabinomannan (LAM) concentrations, a pathogen biomarker for Mycobacterium tuberculosis, in urine, plasma and serum for real-world diagnostic accuracy of pulmonary TB among people living with and without HIV. We conducted a prospective diagnostic study among adults with TB symptoms in South Africa. We measured LAM concentrations in time-matched urine, plasma and serum with an electrochemiluminescence immunoassay using two capture antibodies (FIND 28 and S4-20). From the completed cohort, we randomly selected 210 participants (2 cases: 1 control) based on sensitivity estimates, and we compared diagnostic accuracy of LAM measurements against the microbiological reference standard. Urine and blood specimens from 210 of 684 adults enrolled were tested for LAM. Among 138TB-positive adults (41% female), median urine LAM was 137pg/mL and 52pg/mL by FIND 28 and S4-20, respectively. Average LAM concentrations were highest in HIV-positive participants with CD4+ T cells <200cells/mm3. Urine LAM by S4-20 achieved diagnostic sensitivity of 62% (95% CI: 53%-70%) and specificity of 99% (95% CI: 96%-100%). Plasma and serum LAM by FIND 28 showed similar sensitivity (70%, 95% CI: 62%-78%) and comparable specificities (90%, 95% CI: 82%-97%; 94%, 95% CI: 88%-99%). Diagnostic sensitivity of urine LAM by S4-20 was higher among participants without HIV (41%, 95% CI: 24%-61%) compared to HIV-positive participants with CD4 ≥200cells/mm3 (20%, 95% CI: 8%-39%). Detection of LAM was achievable in non-sputum specimens for pulmonary TB, but additional analyte concentration or signal amplification may be required to achieve diagnostic accuracy targets. Bill and Melinda Gates Foundation.

Detection of mycobacterial lipoarabinomannan in serum for diagnosis of active tuberculosis

Urinary detection of Mycobacterium tuberculosis lipoarabinomannan (LAM) for tuberculosis (TB) diagnosis is well characterized, but the utility of serum LAM detection remains unclear. We developed an assay for serum LAM detection using single-molecule array (Simoa), purified M. tuberculosis LAM, and anti-LAM monoclonal antibodies and evaluated performance on diluted/heat-treated serum samples from patients with and without active TB and/or HIV. The Simoa assay had a limit of detection of 0.35 pg/mL and lower limit of quantification of 0.942 pg/mL. Corrected serum LAM concentrations ranged from 0 to 132.0 pg/mL [median 1.71, interquartile range (IQR) 0.94–6.80] in 90 TB+ patients and from 0 to 2.29 pg/mL (median 1.03, IQR 0.47–1.69) in 55 TB− patients. Using a cutoff of 2.3 pg/mL for 100% specificity, assay sensitivity was 37% in all TB+ subjects (33/90; 95% CI 0.27–0.48), 47% in TB+/HIV+ subjects (26/55; 0.34–0.61), and 60% in TB+/HIV+/smear+ subjects (21/35; 0.42–0.76). Mycobacterial LAM is detectable in serum with high specificity and reasonable sensitivity using Simoa.

Evaluation of lipoarabinomannan in the diagnosis of tuberculosis

The detection of lipoarabinomannan (LAM) antigens in body fluids has several potential advantages compared with the diagnostic methods used currently. The aim of this study was to evaluate the possible role of the detection of LAM in the serum and the urine as a diagnostic aid in the diagnosis of different forms of tuberculosis (TB). This study included 62 newly confirmed tuberculosis cases classified into two groups: group A included patients with pulmonary TB (n=36), and was further divided into two groups: group A1 [the smear-positive pulmonary TB group (n=24)] and group A2 [the smearnegative pulmonary TB group (n=12)]; group B included the extrapulmonary TB group (n=26); and 10 apparently healthy individuals served as the control group. The LAM level was measured in the serum and the urine by an enzyme-linked immunosorbant assay. The mean level of quantitative serum LAM was higher in group A1 (0.55±0.20?ng/ml) compared with group A2 (0.44±0.30?ng/ml) or group B (0.41±0.27?ng/ml). The mean level of quantitative urine LAM was higher in group A1 (0.81±0.24?ng/ml) compared with group B (0.72±0.35?ng/ml) and group A2 (0.65±0.37?ng/ml; P<0.001). The quantitative urine LAM test correlated positively with the degree of bacillary burden (P<0.05). Quantitative serum LAM had a sensitivity of 88.7%, specificity 90%, accuracy 88.9%, positive predictive value 98.2%, and negative predictive value 56.3%. Quantitative urine LAM had a sensitivity of 85.5%, specificity 90%, accuracy 86.1%, positive predictive value 98.1%, and negative predictive value 50%. A combination of serum and urine LAM tests identified that 98.4% of the cases with a positive TB culture correlated with higher serum LAM levels. Advanced chest radiography involvement and TB culture correlated with higher urine LAM levels (P<0.05). The LAM test is a valuable addition in the diagnosis of TB and its different forms. A combination of quantitative serum and urine LAM increased the sensitivity of the test. The quantitative urine LAM test offers additional clinical insight into the degree of TB disease severity and has more applicability.

Mannosylated lipoarabinomannan in serum as a biomarker candidate for subclinical bovine tuberculosis.

BackgroundEarly and unambiguous detection of bovine tuberculosis (bTB), a significant disease of cattle worldwide, is necessary to control the spread of infection to other animals and humans. Current testing strategies are laborious, time consuming and heavily reliant on host responses that do not distinguish bTB from other mycobacteria. We report the presence of a pathogen signature, liparabinomannan (LAM), as a potential biomarker for bTB infection.FindingsFifty-five animals (uninfected [n = 33], bTb [n = 10] and exposed cases [n = 12]) from a well characterized bovine serum repository were screened for the presence of LAM using a commercially available ELISA. Analysis showed that LAM had a sensitivity of 100% and a specificity of 91.7% for bTB detection (bTB positive versus bTB exposed animals).ConclusionLAM detection easily separated bTB infected animals from bTB exposed and negative controls. We propose that pathogen related markers, such as LAM, should be included with current testing strategies as a battery diagnostic for bTB.Electronic supplementary materialThe online version of this article (doi:10.1186/1756-0500-7-559) contains supplementary material, which is available to authorized users.

The value of serum lipoarabinomannan in the diagnosis of pulmonary tuberculosis

Objective The aim of this study was to assess the value of serum lipoarabinomannan (LAM) in the diagnosis of pulmonary tuberculosis (TB). Background The accurate diagnosis of TB is difficult. Recent studies indicate that a LAM assay (ELISA) may have some utility in the diagnosis of TB. Material and methods Sera from 40 individuals with confirmed pulmonary TB and 20 healthy individuals were tested for the presence of LAM by means of ELISA assay. Culture positivity for Mycobacterium tuberculosis was used as the reference standard for TB diagnosis. Results The serum LAM ELISA test showed high positivity in confirmed TB patients; sputum smear combined with LAM diagnosed 95% of the confirmed cases; tuberculin skin test, elevated erythrocyte sedimentation rate, immunocompetent state, and radiological tests have shown significant differences from qualitative and quantitative serum LAM. Serum LAM sensitivity, specificity, accuracy, positive predictive value, and negative predictive value were 90, 100, 93.3, 100, and 83.3%, respectively. Conclusion The LAM test is a simple and reliable test for the diagnosis of pulmonary TB.

Association of lipoarabinomannan with high density lipoprotein in blood: Implications for diagnostics

Understanding the pathophysiology of tuberculosis, and the bio-distribution of pathogen-associated molecules in the host is essential for the development of efficient methods of intervention. One of the key virulence factors in the pathology of tuberculosis infection is Lipoarabinomannan (LAM). Previously, we have demonstrated the reliable detection of LAM in urine from tuberculosis patients in a sandwich immunoassay format. We have also applied an ultra-sensitive detection strategy developed for amphiphilic biomarkers, membrane insertion, to the detection of LAM with a limit of detection of 10 fM. Herein, we evaluate the application of membrane insertion to the detection of LAM in patient serum, and demonstrate that the circulating concentrations of 'monomeric' LAM in serum are very low, despite significantly higher concentrations in the urine. Using spiked samples, we demonstrate that this discrepancy is due to the association of LAM with high-density lipoprotein (HDL) nanodiscs in human serum. Indeed, pull-down of HDL nanodiscs from human serum allows for the recovery of HDL-associated LAM. These studies suggest that LAM is likely associated with carrier molecules such as HDL in the blood of patients infected with tuberculosis. This phenomenon may not be limited to LAM in that many pathogen-associated molecular patterns like LAM are amphiphilic in nature and may also be associated with host lipid carriers. Such interactions are likely to affect host-pathogen interactions, pathogen bio-distribution and clearance in the host, and must be thoroughly understood for the effective design of vaccines and diagnostics.

Challenges facing lipoarabinomannan urine antigen tests for diagnosing HIV-associated tuberculosis

Challenges facing lipoarabinomannan urine antigen tests for diagnosing HIV-associated tuberculosis