[Progress in lipoarabinomannan antigen detection for tuberculosis diagnosis in people living with HIV/AIDS].

Tuberculosis (TB) is the leading cause of death among people living with HIV/AIDS (PLWHA), posing a significant disease burden. Early TB screening in PLWHA is a key intervention to reduce transmission and control disease progression. ​Lipoarabinomannan (LAM) is a glycolipid of Mycobacterium tuberculosis (MTB) that can be detected in the urine of tuberculosis patients. LAM is useful for the rapid and accurate diagnosis of tuberculosis. This article reviews LAM and its application and limitations in the diagnosis of PLWHA, hoping to provide a reference for the diagnosis of tuberculosis in PLWHA.

Diagnostic accuracy of Lipoarabinomannan detection by lateral flow assay in pleural tuberculosis.

BACKGROUND: Lipoarabinomannan (LAM) antigen serves as an attractive biomarker to diagnose Tuberculosis (TB). Given the limitations of current diagnostic modalities for Pleural TB, current study evaluated LAM's potential to serve as a point-of-care test to diagnose pleural TB. METHODS: A cross sectional, diagnostic accuracy study was conducted during February to November 2021 in a tertiary care hospital in India. LAM antigen detection was performed on pleural fluid as well as early morning urine specimen of suspected pleural TB patients by "Alere/ Abott Determine TB LAM" lateral flow assay (LAM-LFA). The results were compared to microbiological reference standards/MRS (Mycobacterial culture or NAAT) and Composite reference standards/CRS (MRS plus Clinico-radiological diagnosis). RESULTS: A total of 170 subjects were included in the analysis, including 26 with Definite TB, 22 with Probable TB, and 122 with No TB. Compared to MRS and CRS, the sensitivity (61.54% & 45.83%) and positive predictive value (PPV) (57.14 & 78.57%) of Pleural LAM-LFA testing were found to be suboptimal, whereas the specificity (91.67% & 95.08%) and negative predictive value (NPV) (92.96% & 81.69%) of the assay were found to be good. Urinary LAM-LFA performed even worse than pleural LAM-LFA, except for its higher specificity against MRS and CRS (97.2% and 98.3%, respectively). Specificity and PPV of pleural LAM detection increased to 100% when analysed in a subgroup of patients with elevated ADA levels (receiver operating curve analysis-derived cut off value > 40 IU/ml). CONCLUSION: Detection of LAM antigen by LFA directly from pleural fluid was found to be a useful test to predict absence of the disease if the test is negative rather than using as a POCT for diagnosis.

Diagnostic yield of urine lipoarabinomannan and sputum tuberculosis tests in people living with HIV: a systematic review and meta-analysis of individual participant data.

BACKGROUND: Sputum is the most widely used sample to diagnose active tuberculosis, but many people living with HIV are unable to produce sputum. Urine, in contrast, is readily available. We hypothesised that sample availability influences the diagnostic yield of various tuberculosis tests. METHODS: In this systematic review and meta-analysis of individual participant data, we compared the diagnostic yield of point-of-care urine-based lipoarabinomannan tests with that of sputum-based nucleic acid amplification tests (NAATs) and sputum smear microscopy (SSM). We used microbiologically confirmed tuberculosis based on positive culture or NAAT from any body site as the denominator and accounted for sample provision. We searched PubMed, Web of Science, Embase, African Journals Online, and clinicaltrials.gov from database inception to Feb 24, 2022 for randomised controlled trials, cross-sectional studies, and cohort studies that assessed urine lipoarabinomannan point-of-care tests and sputum NAATs for active tuberculosis detection in participants irrespective of tuberculosis symptoms, HIV status, CD4 cell count, or study setting. We excluded studies in which recruitment was not consecutive, systematic, or random; provision of sputum or urine was an inclusion criterion; less than 30 participants were diagnosed with tuberculosis; early research assays without clearly defined cutoffs were tested; and humans were not studied. We extracted study-level data, and authors of eligible studies were invited to contribute deidentified individual participant data. The main outcomes were the tuberculosis diagnostic yields of urine lipoarabinomannan tests, sputum NAATs, and SSM. Diagnostic yields were predicted using Bayesian random-effects and mixed-effects meta-analyses. This study is registered with PROSPERO, CRD42021230337. FINDINGS: We identified 844 records, from which 20 datasets and 10 202 participants (4561 [45%] male participants and 5641 [55%] female participants) were included in the meta-analysis. All studies assessed sputum Xpert (MTB/RIF or Ultra, Cepheid, Sunnyvale, CA, USA) and urine Alere Determine TB LAM (AlereLAM, Abbott, Chicago, IL, USA) in people living with HIV aged 15 years or older. Nearly all (9957 [98%] of 10 202) participants provided urine, and 82% (8360 of 10 202) provided sputum within 2 days. In studies that enrolled unselected inpatients irrespective of tuberculosis symptoms, only 54% (1084 of 1993) of participants provided sputum, whereas 99% (1966 of 1993) provided urine. Diagnostic yield was 41% (95% credible interval [CrI] 15-66) for AlereLAM, 61% (95% Crl 25-88) for Xpert, and 32% (95% Crl 10-55) for SSM. Heterogeneity existed across studies in the diagnostic yield, influenced by CD4 cell count, tuberculosis symptoms, and clinical setting. In predefined subgroup analyses, all tests had higher yields in symptomatic participants, and AlereLAM yield was higher in those with low CD4 counts and inpatients. AlereLAM and Xpert yields were similar among inpatients in studies enrolling unselected participants who were not assessed for tuberculosis symptoms (51% vs 47%). AlereLAM and Xpert together had a yield of 71% in unselected inpatients, supporting the implementation of combined testing strategies. INTERPRETATION: AlereLAM, with its rapid turnaround time and simplicity, should be prioritised to inform tuberculosis therapy among inpatients who are HIV-positive, regardless of symptoms or CD4 cell count. The yield of sputum-based tuberculosis tests is undermined by people living with HIV who cannot produce sputum, whereas nearly all participants are able to provide urine. The strengths of this meta-analysis are its large size, the carefully harmonised denominator, and the use of Bayesian random-effects and mixed-effects models to predict yields; however, data were geographically restricted, clinically diagnosed tuberculosis was not considered in the denominator, and little information exists on strategies for obtaining sputum samples. FUNDING: FIND, the Global Alliance for Diagnostics.

Brief Report: Detection of Urine Lipoarabinomannan Is Associated With Proinflammatory Innate Immune Activation, Impaired Host Defense, and Organ Dysfunction in Adults With Severe HIV-Associated Tuberculosis in Uganda.

BACKGROUND: The immunopathology of disseminated HIV-associated tuberculosis (HIV/TB), a leading cause of critical illness and death among persons living with HIV in sub-Saharan Africa, is incompletely understood. Reflective of hematogenously disseminated TB, detection of lipoarabinomannan (LAM) in urine is associated with greater bacillary burden and poor outcomes in adults with HIV/TB. METHODS: We determined the relationship between detection of urine TB-LAM, organ dysfunction, and host immune responses in a prospective cohort of adults hospitalized with severe HIV/TB in Uganda. Generalized additive models were used to analyze the association between urine TB-LAM grade and concentrations of 14 soluble immune mediators. Whole-blood RNA-sequencing data were used to compare transcriptional profiles between patients with high- vs. low-grade TB-LAM results. RESULTS: Among 157 hospitalized persons living with HIV, 40 (25.5%) had positive urine TB-LAM testing. Higher TB-LAM grade was associated with more severe physiologic derangement, organ dysfunction, and shock. Adjusted generalized additive models showed that higher TB-LAM grade was significantly associated with higher concentrations of mediators reflecting proinflammatory innate and T-cell activation and chemotaxis (IL-8, MIF, MIP-1ß/CCL4, and sIL-2Ra/sCD25). Transcriptionally, patients with higher TB-LAM grades demonstrated multifaceted impairment of antibacterial defense including reduced expression of genes encoding cytotoxic and autophagy-related proteins and impaired cross-talk between innate and cell-mediated immune effectors. CONCLUSIONS: Our findings add to emerging data suggesting pathobiological relationships between LAM, TB dissemination, innate cell activation, and evasion of host immunity in severe HIV/TB. Further translational studies are needed to elucidate the role for immunomodulatory therapies, in addition to optimized anti-TB treatment, in this often critically ill population.

Novel FujiLAM assay to detect tuberculosis in HIV-positive ambulatory patients in four African countries: a diagnostic accuracy study.

BACKGROUND: Development of rapid biomarker-based tests that can diagnose tuberculosis using non-sputum samples is a priority for tuberculosis control. We aimed to compare the diagnostic accuracy of the novel Fujifilm SILVAMP TB LAM (FujiLAM) assay with the WHO-recommended Alere Determine TB-LAM Ag test (AlereLAM) using urine samples from HIV-positive patients. METHODS: We did a diagnostic accuracy study at five outpatient public health facilities in Uganda, Kenya, Mozambique, and South Africa. Eligible patients were ambulatory HIV-positive individuals (aged ≥15 years) with symptoms of tuberculosis irrespective of their CD4 T-cell count (group 1), and asymptomatic patients with advanced HIV disease (CD4 count <200 cells per µL, or HIV clinical stage 3 or 4; group 2). All participants underwent clinical examination, chest x-ray, and blood sampling, and were requested to provide a fresh urine sample, and two sputum samples. FujiLAM and AlereLAM urine assays, Xpert MTB/RIF Ultra assay on sputum or urine, sputum culture for Mycobacterium tuberculosis, and CD4 count were systematically carried out for all patients. Sensitivity and specificity of FujiLAM and AlereLAM were evaluated against microbiological and composite reference standards. FINDINGS: Between Aug 24, 2020 and Sept 21, 2021, 1575 patients (823 [52·3%] women) were included in the study: 1031 patients in group 1 and 544 patients in group 2. Tuberculosis was microbiologically confirmed in 96 (9·4%) of 1022 patients in group 1 and 18 (3·3%) of 542 patients in group 2. Using the microbiological reference standard, FujiLAM sensitivity was 60% (95% CI 51-69) and AlereLAM sensitivity was 40% (31-49; p<0·001). Among patients with CD4 counts of less than 200 cells per µL, FujiLAM sensitivity was 69% (57-79) and AlereLAM sensitivity was 52% (40-64; p=0·0218). Among patients with CD4 counts of 200 cells per µL or higher, FujiLAM sensitivity was 47% (34-61) and AlereLAM sensitivity was 24% (14-38; p=0·0116). Using the microbiological reference standard, FujiLAM specificity was 87% (95% CI 85-89) and AlereLAM specificity was 86% (95 CI 84-88; p=0·941). FujiLAM sensitivity varied by lot number from 48% (34-62) to 76% (57-89) and specificity from 77% (72-81) to 98% (93-99). INTERPRETATION: Next-generation, higher sensitivity urine-lipoarabinomannan assays are potentially promising tests that allow rapid tuberculosis diagnosis at the point of care for HIV-positive patients. However, the variability in accuracy between FujiLAM lot numbers needs to be addressed before clinical use. FUNDING: ANRS and Médecins Sans Frontières.

Exploring the eligibility of all reported lipoarabinomannan-testing assays in different clinical situations: a systematic review and meta-analysis of 97 articles.

OBJECTIVES: How to choose proper lipoarabinomannan-testing assays for diagnosing tuberculosis (TB) in different populations baffles clinicians. This work assessed all reported lipoarabinomannan assays' performance and aimed to identify the eligibility of each assay and offer guidance for clinicians. METHODS: We searched PubMed, Embase, and Web of Science until August 23, 2020. The risk of bias was evaluated by QADAS-2. Heterogeneity was evaluated by the Cochran Q test and I2. Sensitivity and specificity were pooled by a bivariate mixed model (register number: CRD42021270506). RESULTS: A total of 97 articles, covering 144 trials, 16 assays, 45,679 participants, and eight sample types, were divided into five groups. Electrochemiluminescence (ECL) had a sensitivity of 65%, specificity of 92%, and an area under curve (AUC) of 0.85 in diagnosing pulmonary TB in adults. ECL showed a promising diagnostic ability (sensitivity: 78%; specificity: 88%; AUC: 0.88) in patients with HIV, especially for urine detection (sensitivity: 90%; specificity: 89%; AUC: 0.95). The enzyme-linked immune assay showed a preference for diagnosing TB in Asians and Africans, especially in Africans who were smear-positive (sensitivity: 80%; specificity: 88%; AUC: 0.91). CONCLUSION: ECL was recommended for diagnosing pulmonary TB in adults, especially for TB/HIV co-infection. Taking urine as a sample further enhanced ECL's diagnostic performance. Enzyme-linked immune assay was recommended as an additional TB-related detection for smear-positive Africans.

Complementary Nonsputum Diagnostic Testing for Tuberculosis in People with HIV Using Oral Swab PCR and Urine Lipoarabinomannan Detection.

Testing for mycobacterial lipoarabinomannan (LAM) in urine is a practical but insensitive alternative to sputum testing to diagnose tuberculosis (TB) in people with HIV (PWH). Here, we evaluated urine LAM testing alongside PCR-based tests for Mycobacterium tuberculosis (MTB) DNA in tongue swabs. We hypothesized that the two nonsputum samples would deliver complementary, not redundant, results. The study included 131 South African patients of whom 64 (48.1%) were confirmed to have TB by GeneXpert MTB/RIF Ultra (Xpert Ultra) or culture analysis of sputum. A total of 120 patients (91.6%) were coinfected with HIV and 130 yielded a valid urine LAM result (Alere DETERMINE LAM Ag). Tongue swab samples were tested by IS6110-targeted qPCR with a quantification cycle (Cq) cutoff of 32. Relative to reference sputum testing (TB culture and Xpert Ultra), combined urine LAM and oral swab testing (either sample positive) was significantly more sensitive than either nonsputum sample alone (57% sensitivity for combined testing versus 35% and 39% sensitivity for urine LAM and tongue swabs; P = 0.01 and 0.04, respectively). Specificity of combined testing (neither sample positive) was 97%. On average, tongue swab-positive participants had higher sputum signal strength than urine-LAM positive participants, as measured by sputum Xpert Ultra Cq value (P = 0.037). A subset of tongue swabs (N = 18) was also tested by using Xpert Ultra, which reproduced true positive and true negative IS6110 qPCR results and resolved the two false-positive tongue swabs. With further development, tongue swabs and urine may feasibly serve as complementary nonsputum samples for diagnosis of TB in PWH.

Uptake of the lateral flow urine LAM test in Europe and Central Asia.

INTRODUCTION: Since 2015 (updated in 2019), the WHO has recommended to include the commercial lateral flow urine lipoarabinomannan TB test (LF-LAM), AlereLAM, in the diagnostic toolkit for severely ill people living with HIV.METHODS: To assess the current use and barriers to the implementation of the test, we conducted an electronic survey among national focal points and managers of TB and HIV programmes in the 53 Member States of the WHO European Region and a European network of clinicians working in TB and HIV medicine.RESULTS: In all, 45 individual responses (37 countries) were received from programme managers and focal points and 17 responses (14 countries) from clinicians. Only eight countries reported adopting LF-LAM policies, with only four currently using the AlereLAM (Armenia, Belarus, Ukraine and Uzbekistan). The most commonly reported barriers to implementing the test were the small number of eligible patients (with HIV-TB co-infections), the test not being included in the TB or HIV programme´s mandate and lack of budget allocation.CONCLUSION: Consistent with findings from high TB burden countries in Africa and Asia, the survey demonstrated that uptake of AlereLAM is almost non-existent. Addressing the identified barriers and the intrinsic limitations of the test could help to increase the use of the test.

Lateral flow urine lipoarabinomannan assay for extrapulmonary tuberculosis diagnosis in adults who are HIV-positive.

BACKGROUND: The diagnosis of extrapulmonary tuberculosis (EPTB) in patients with HIV remains a challenge for clinicians. The World Health Organization recommends the detection of lipoarabinomannan (LAM) for diagnosing pulmonary tuberculosis in patients with HIV. A new generation of urine LAM tests (FujiLAM®) is available. However, studies regarding its accuracy are limited. OBJECTIVE: This study aimed to evaluate the accuracy of urine LAM tests using FujiLAM® for diagnosing EPTB in patients with HIV. METHODS: A cross-sectional study using urine samples of patients at Cipto Mangunkusumo Hospital, Indonesia, was performed from January 2020 to December 2020. Fresh urine was applied to the FujiLAM®. Patients were grouped into definitive, probable, and non-TB groups. The diagnostic accuracy of the urine LAM test was compared with other Mycobacterium tuberculosis specimen gold standard tests. RESULTS: Among 62 patients, 16 patients (25.8%) had definitive diagnosis of EPTB. Among those with definitive TB, an urine LAM test yielded a sensitivity of 75% (95% confidence interval [CI]: 47.62-92.73%) and specificity of 73.91% (95% CI: 87-85.73%). Meanwhile, compared with all diagnostic tests (definite + probable TB), FujiLAM® had a sensitivity value of 61% (95% CI 43.36-76.86%) and a specificity value of 92.31% (95% CI 74.87-99.05%). CONCLUSION: The FujiLAM® test is a feasible method for diagnosing EPTB in patients with HIV.

Implementation of tuberculosis and cryptococcal meningitis rapid diagnostic tests amongst patients with advanced HIV at Kamuzu Central Hospital, Malawi, 2016-2017.

BACKGROUND: Cryptococcal meningitis (CM) and tuberculosis (TB) remain leading causes of hospitalization and death amongst people living with HIV, particularly those with advanced HIV disease. In hospitalized patients, prompt diagnosis of these diseases may improve patient outcomes. The advanced HIV rapid diagnostic tests such as determine TB urine lipoarabinomannan lateral flow assay (urine LAM), urine X-pert MTB/RIF assay (urine X-pert), and serum/blood cryptococcal antigen test (serum CrAg) are recommended but frequently not available in many resource-limited settings. We describe our experience providing these tests in a routine hospital setting. METHOD: From 1 August 2016 to 31 January 2017, a prospective cohort study to diagnose TB and Cryptococcal meningitis using point of care tests was conducted in the medical wards at Kamuzu Central Hospital, in Lilongwe, Malawi. The tests offered were PIMA CD4 cell count, serum CrAg, urine LAM, and urine X-pert. The testing was integrated into an existing HIV/TB treatment room on the wards and performed close to admission time. Patients were followed until discharge or death in the ward. RESULTS: We included 438 HIV-positive patients; 76% had a previously known HIV diagnosis (87% already on ART). We measured CD4 count in 365/438 (83%), serum CrAg in 301/438 (69%), urine LAM in 363/438 (83%), and urine X-pert in 292/438 (67%). The median CD4 count was 144 cells/ml (IQR 46-307). Serum CrAg positivity rate was 23 /301 (8%) and CM was confirmed by CSF Crag in 13/23 (56%). The majority of CM patients 9/13 (69%) started antifungal therapy within two days of diagnosis. Urine LAM and urine X-pert positivity rates were 81/363(22%) and (14/292 (5%) respectively. The positivity rate of urine LAM was higher in patients with low CD4 cell counts (< 100 cells/ml) and low BMI (< 18.5). Most patients with positive urine LAM started TB treatment on the same day. Despite the early diagnosis and treatment of TB and CM, the inpatient mortality was high; 30% and 25% respectively. CONCLUSION: Although advanced HIV rapid diagnostic tests are recommended, one key challenge in implementation is the limited trained personnel administering the tests. Despite the effective use of the point of care tests in the clinical care of hospitalized TB and CM patients, mortality among these patients remained unacceptably high. Henceforth we need to train other cadres apart from nurses, clinicians, and laboratory technicians to conduct the tests. There is an urgent need to identify and modify other risks of death from TB and CM. TRIAL REGISTRATION: Malawi National Health Science Research committee: Protocol # 1144. Registered 2 July 2014 and University Of North Carolina IRB #: UNCPM 21412, approved 13th October 2014.

Tailor made: New insights into lipoarabinomannan structure may improve TB diagnosis.

Detecting the mycobacterial glycolipid lipoarabinomannan (LAM) in urine by anti-LAM antibodies fills a gap in the diagnostic armamentarium of much needed simple rapid tests for tuberculosis, but lacks high sensitivity in all patient groups. A better understanding of LAM structure from clinically relevant strains may allow improvements in diagnostic performance. De et al. have recently determined the structures of LAM from three epidemiologically important lineages of Mycobacterium tuberculosis and probed their interaction with an anti-LAM monoclonal antibody. Their results not only identify a series of tailoring modifications that impact antibody binding but also provide a roadmap for improving U-LAM-based diagnostics.

Utility of urine lipoarabinomannan (LAM) in diagnosing mycobacteria infection among hospitalized HIV-positive patients.

OBJECTIVES: Cross-reactivity with nontuberculous mycobacteria (NTM) species might limit the use of urine lipoarabinomannan (LAM) test to diagnose tuberculosis (TB) in people living with HIV (PLWH). This study aimed to investigate the utility of the LAM test among hospitalized HIV-positive patients. METHODS: This prospective study enrolled HIV-positive inpatients with any TB symptom or seriously ill patients with advanced immunodeficiency. Urine samples were tested using the Alere Determine LAM Ag, and participants were categorized as confirmed TB, confirmed NTM infection, unclassified mycobacteria infection, and no mycobacteria infection based on microbiologic reference standards. RESULTS: A total of 382 participants were included. The prevalence of confirmed TB and NTM infection was 5.24% (20 of 382) and 4.45% (17 of 382), respectively. The sensitivity and specificity of the urine LAM for TB diagnosis were 65.00% (95% confidence interval [CI] 40.78-84.61) and 89.36% (95% CI 85.68-92.36), respectively. The LAM test for NTM yielded a sensitivity of 58.82% (95% CI 32.92-81.56) and specificity of 88.61% (95% CI 84.87-91.70). Notably, the negative predictive values of the urine LAM for TB and NTM were 97.85% (95% CI 95.63-99.13) and 97.85% (95% CI 95.63-99.13), respectively. CONCLUSIONS: Cross-reactivity with NTM cause high false-positive LAM for TB diagnosis in PLWH. The correct identification of mycobacteria species is crucial for deciding treatment strategies.

Diagnostic value of Lipoarabinomannan antigen for detecting Mycobacterium tuberculosis in adults and children with or without HIV infection.

OBJECTIVES: Even today, tuberculosis (TB) remains a leading public health problem; yet, the current diagnostic methods still have a few shortcomings. Lipoarabinomannan (LAM) provides an opportunity for TB diagnosis, and urine LAM detection seems to have a promising and widely applicable prospect. DESIGN OR METHODS: Four databases were systematically searched for eligible studies, and the quality of the studies was evaluated using the quality assessment of diagnostic accuracy studies-2 (QUADAS-2). Graphs and tables were created to show sensitivity, specificity, likelihood ratios, diagnostic odds ratio (DOR), the area under the curve (AUC), and so on. RESULTS: Based on the included 67 studies, the pooled sensitivity of urine LAM was 48% and specificity was 89%. In the subgroup analyses, the FujiLAM test had higher sensitivity (69%) and specificity (92%). Furthermore, among patients infected with human immunodeficiency virus (HIV), 50% of TB patients were diagnosed using a urine LAM test. Besides, the CD4+ cell count was inversely proportional to the sensitivity. CONCLUSIONS: Urine LAM is a promising diagnostic test for TB, particularly using the FujiLAM in HIV-infected adults whose CD4+ cell count is ≤100 per µl. Besides, the urine LAM test shows various sensitivities and specificities in different subgroups in terms of age, HIV infection status, CD4+ cell count, and testing method.

Immobilization of Proteinase K for urine pretreatment to improve diagnostic accuracy of active tuberculosis.

The World Health Organization (WHO) calls for the development of a rapid, biomarker-based, non-sputum test capable of detecting all forms of tuberculosis (TB) at the point-of-care to enable immediate treatment initiation. Lipoarabinomannan (LAM) is the only WHO-endorsed TB biomarker that can be detected in urine, an easily collected sample matrix. For obtaining optimal sensitivity, we and others have shown that some form of sample pretreatment is necessary to remove background from patient urine samples. A number of systems are paper-based often destined for resource limited settings. Our current work presents incorporation of one such sample pretreatment, proteinase K (ProK) immobilized on paper (IPK) and test its performance in comparison to standard proteinase K (SPK) treatment that involves addition and deactivation at high temperature prior to performing a capture ELISA. Herein, a simple and economical method was developed for using ProK immobilized strips to pretreat urine samples. Simplification and cost reduction of the proposed pretreatment strip were achieved by using Whatman no.1 paper and by minimizing the concentration of ProK (an expensive but necessary reagent) used to pretreat the clinical samples prior to ELISA. To test the applicability of IPK, capture ELISA was carried out on either LAM-spiked urine or the clinical samples after pretreatment with ProK at 400 µg/mL for 30 minutes at room temperature. The optimal conditions and stability of the IPK were tested and validation was performed on a set of 25 previously analyzed archived clinical urine samples with known TB and HIV status. The results of IPK and SPK treated samples were in agreement showing that the urine LAM test currently under development has the potential to reach adult and pediatric patients regardless of HIV status or site of infection, and to facilitate global TB control to improve assay performance and ultimately treatment outcomes.

Field evaluation of a prototype tuberculosis lipoarabinomannan lateral flow assay on HIV-positive and HIV-negative patients.

Detection of tuberculosis at the point-of-care (POC) is limited by the low sensitivity of current commercially available tests. We describe a diagnostic accuracy field evaluation of a prototype urine Tuberculosis Lipoarabinomannan Lateral Flow Assay (TB-LAM LFA) in both HIV-positive and HIV-negative patients using fresh samples with sensitivity and specificity as the measures of accuracy. This prototype combines a proprietary concentration system with a sensitive LFA. In a prospective study of 292 patients with suspected pulmonary tuberculosis in Uganda, the clinical sensitivity and specificity was compared against a microbiological reference standard including sputum Xpert MTB/RIF Ultra and solid and liquid culture. TB-LAM LFA had an overall sensitivity of 60% (95%CI 51-69%) and specificity of 80% (95%CI 73-85%). When comparing HIV-positive (N = 86) and HIV-negative (N = 206) patients, there was no significant difference in sensitivity (sensitivity difference 8%, 95%CI -11% to +24%, p = 0.4351) or specificity (specificity difference -9%, 95%CI -24% to +4%, p = 0.2051). Compared to the commercially available Alere Determine TB-LAM Ag test, the TB-LAM LFA prototype had improved sensitivity in both HIV-negative (difference 49%, 95%CI 37% to 59%, p<0.0001) and HIV-positive patients with CD4+ T-cell counts >200cells/µL (difference 59%, 95%CI 32% to 75%, p = 0.0009). This report is the first to show improved performance of a urine TB LAM test for HIV-negative patients in a high TB burden setting. We also offer potential assay refinement solutions that may further improve sensitivity and specificity.

Potential value of urine lateral-flow lipoarabinomannan (LAM) test for diagnosing tuberculosis among severely acute malnourished children.

BACKGROUND: Tuberculosis (TB) is a serious co-morbidity among children with severe acute malnutrition (SAM) and TB diagnosis remains particularly challenging in the very young. We explored whether, in a low HIV-prevalence setting, the detection of mycobacterial lipoarabinomannan (LAM) antigen in urine may assist TB diagnosis in SAM children, a pediatric population currently not included in LAM-testing recommendations. To that end, we assessed LAM test-positivity among SAM children with and without signs or symptoms of TB. METHODS: A cross-sectional assessment (February 2016-August 2017) included children <5 years with SAM from an Intensive-Therapeutic-Feeding-Centre in Madaoua, Niger. Group 1: children with signs or symptoms suggestive of TB. Group 2: children without any sign or symptom of TB. Urine-specimens were subjected to DetermineTM TB-LAM lateral-flow-test (using a 4-grade intensity scale for positives). LAM-results were used for study purposes and not for patient management. Programmatic TB-diagnosis was primarily based on patients' clinical symptoms and TB contact history with no systematic access to X-ray or microbiological reference testing. RESULTS: 102 (Group 1) and 100 children (Group 2) were included (median age 18 months, 59.4% male, 1.0% HIV-positive). In Group 1, 22 (21.6%) children were started on TB-treatment (probable TB) and none of the children in Group 2. LAM-positivity was 52.0% (53/102) and 37.0% (37/100) in Group 1 and 2, respectively. Low-intensity (Grade 1) LAM test-positivity was similarly high in both Groups (37.3% and 36.0%, respectively), while Grade 2 or 3-positives were mainly detected in Group 1 (Group 1: 14.7%, Group 2: 1.0%, p<0.001). When considering only Grades >1 as positive, LAM-testing detected 22.7% (95%CI: 7.8, 45.4) among probable TB cases, while 99% (95%CI: 94.6, 99.9) of unlikely TB cases (Group 2) tested negative. CONCLUSION: These findings suggest the potential utility of LAM urine testing in HIV-negative children with SAM. Determine LAM-positivity with Grades >1 may identify HIV-negative SAM children that are eligible for rapid TB-treatment initiation, though low-intensity (Grade 1) LAM-positive results may not be helpful in this way. Further studies in this specific pediatric population are warranted, including evaluations of new generation LAM tests.

The utility of point-of-care urinary lipoarabinomannan testing for the diagnosis of tuberculosis in critically ill patients: a prospective observational study.

BACKGROUND: Tuberculosis is a major global public health concern. Patients with tuberculosis who require critical care have a high mortality and delay in initiating antituberculous therapy is associated with increased mortality. Lipoarabinomannan (LAM) is a lipopolysaccharide found in the cell wall of Mycobacterium tuberculosis. Urinary LAM may be used as a bedside diagnostic test for tuberculosis. METHODS: The study was a single centre, prospective observational study that compared the utility of urinary LAM with conventional tuberculosis diagnostic modalities in patients with suspected tuberculosis who required intensive care admission. Urinary LAM testing was performed using the Alere Determine TB LAM Ag lateral flow assay test strips. A patient was classified as having confirmed tuberculosis if they met the following criteria: a clinical presentation compatible with tuberculosis, with either a positive TB culture, a positive GeneXpert, or a histological diagnosis of tuberculosis. RESULTS: Fifty patients were included in the study, with 12 having confirmed tuberculosis. All patients received mechanical ventilation, and the ICU mortality was 60%. Urinary LAM had a sensitivity of 50.0% (95% CI, 21.1 to 78.9%) and a specificity of 84.2% (95% CI, 68.8 to 94.0%) for confirmed tuberculosis. CONCLUSION: Urinary LAM allows for rapid bedside diagnosis of tuberculosis in critically ill patients. A positive urinary LAM should prompt consideration to initiate antituberculous treatment while the results of further diagnostic testing are awaited.

Urine lipoarabinomannan in HIV uninfected, smear negative, symptomatic TB patients: effective sample pretreatment for a sensitive immunoassay and mass spectrometry.

Our study sought to determine whether urine lipoarabinomannan (LAM) could be validated in a sample cohort that consisted mainly of HIV uninfected individuals that presented with tuberculosis symptoms. We evaluated two tests developed in our laboratory, and used them on clinical samples from Lima, Peru where incidence of HIV is low. ELISA analysis was performed on 160 samples (from 140 adult culture-confirmed TB cases and 20 symptomatic TB-negative child controls) using 100 µL of urine after pretreatment with Proteinase K. Two different mouse monoclonal antibodies-CS35 and CHCS9-08 were used individually for capture of urine LAM. Among cases, optical density (OD450) values had a positive association with higher bacillary loads. The 20 controls had negative values (below the limit of detection). The assay correctly identified all samples (97-100% accuracy confidence interval). For an alternate validation of the ELISA results, we analyzed all 160 urine samples using an antibody independent chemoanalytical approach. Samples were called positive only when LAM surrogates-tuberculostearic acid (TBSA) and D-arabinose (D-ara)-were found to be present in similar amounts. All TB cases, including the 40 with a negative sputum smear had LAM in detectable quantities in urine. None of the controls had detectable amounts of LAM. Our study shows that urinary LAM detection is feasible in HIV uninfected, smear negative TB patients.

High-sensitivity C-reactive protein in HIV care: Tuberculosis diagnosis and short-term mortality in a cohort of Kenyan HIV patients in the DREAM programme.

OBJECTIVE: Tuberculosis (TB) is the leading cause of death in HIV-positive people. In Kenya, 140 000 new TB cases occurred in 2019, and 13 000 HIV-positive patients died due to TB. The objective of this study was to investigate the role of high-sensitivity C-reactive protein (HS-CRP) in TB diagnosis and the prediction of mortality in HIV-positive patients. METHODS: The IDEA-TB Study enrolled HIV-positive adult patients attending three DREAM centres in Kenya who were suspected of having TB. A lateral flow urine lipoarabinomannan assay (LF-LAM), serum HS-CRP, and GeneXpert MTB/RIF assay (Xpert MTB/RIF) were performed. Six-month survival was evaluated. RESULTS: A total of 574 patients were enrolled. The median (interquartile range) age, body mass index, and CD4 count were 45 years (37-54 years), 20.5 kg/m2 (18.5-23.69 kg/m2), and 477 cells/mL (290-700 cells/mL), respectively. TB was confirmed in 87 (15.2%) patients. Concordance between the Xpert MTB/RIF and LF-LAM tests was 87.1%. HS-CRP was higher in TB patients (35.39 mg/l vs 9.21 mg/l). Malnutrition and elevated HS-CRP were associated with TB: odds ratio (OR) 2.5 (95% confidence interval (CI) 1.14-5.72) and OR 6.6 (95% CI 3.87-11.52), respectively. Nine (1.6%) patients died during follow-up. No single factor was associated with mortality. Only the combination of malnutrition and elevated HS-CRP was highly predictive of death (odds ratio (OR) 9.8, 95% CI 1.88-50.95); the association was stronger in TB patients (33.3% vs 1.0%; OR 47.6, 95% CI 7.03-322.23). CONCLUSION: TB diagnosis in HIV-positive patients remains challenging. HS-CRP could play a role in predicting early mortality in symptomatic patients.