Urine Lipoarabinomannan Testing Research Articles

Urine lipoarabinomannan concentrations among HIV-negative adults with pulmonary or extrapulmonary tuberculosis disease in Vietnam.

Lipoarabinomannan (LAM) is a promising target biomarker for diagnosing subclinical and clinical tuberculosis (TB). Urine LAM (uLAM) testing using rapid diagnostic tests (RDTs) has been approved for people living with HIV (PLWH), however there is limited data regarding uLAM levels in HIV-negative (HIV-ve) adults with clinical TB. We conducted a clinical study of adults presenting with clinical TB-related symptoms at the National Lung Hospital in Hanoi, Vietnam. The uLAM concentrations were measured using electrochemiluminescent (ECL) immunoassays and compared to a microbiological reference standard (MRS) using GeneXpert Ultra and TB culture testing. Estimated uLAM concentrations above plate specific calculated limit of detection (LOD) were considered uLAM positive. Additional microbiological testing was conducted for possible extrapulmonary TB (EPTB). Among 745 participants enrolled, 335 (44.9%) participants with presumptive pulmonary TB (PTB) and 6 (11.3%) participants with presumptive EPTB had confirmed TB disease. Overall, the S/A antibody pair had a sensitivity of 39% (95% Confidence Interval [CI] 0.33, 0.44) and a specificity of 97% (95% CI 0.96, 0.99) compared to the MRS. The F/A antibody pair had a sensitivity of 41% (95% CI 0.35, 0.47) and a specificity of 79% (95% CI 0.75, 0.84). S/A provided greater discriminatory ability compared to F/A for both individuals with presumptive PTB (AUROC: 0.74 vs 0.63, p<0.0001) and presumptive EPTB (0.76 vs 0.54, p = 0.045) when using the MRS. Among HIV-ve participants in an adult cohort in Vietnam, the concentrations of uLAM remained relatively low for people with clinical TB, which may present challenges for improving RDT sensitivity.

What is New in the Diagnosis of Childhood Tuberculosis?

The fact that almost half of the 1 million cases of childhood tuberculosis (TB)globally remain undiagnosed jeopardizes the TB elimination goal. Fortunately, there are new advances in this fieldwhich have the potential to bridge this diagnostic gap. Advances in imaging include computer assisted interpretation of chest X-rays (CXRs), point of care ultrasound (POCUS) and faster and superior computed tomography/ magnetic resonance imaging (CT/ MRI) protocols. The urine lipoarabinomannan test has proved to be a good point of care test for diagnosing TB in Human immunodeficiency virus (HIV) infected children. Stool and nasopharyngeal aspirates are emerging as acceptable alternatives for gastric lavage and induced sputum for diagnosing intrathoracic tuberculosis. Xpert MTB/RIF Ultra has improved sensitivitycompared to Xpert MTB/RIF for diagnosing both pulmonary/ extrapulmonary TB. Xpert XDR is another commercially available accurate point of care test for detecting resistance to drugs other than rifampicin in smear positive samples. Other molecular methods including new line probe assays, pyrosequencing, whole genome sequencing, and targeted next generation sequencing are extremely promising but not available commercially at present. The C-Tb skin test isan acceptable alternative to the tuberculin skin test and interferon gamma release assays for diagnosis of latent infection. There is an urgent need to incorporate some of these advances in the existingdiagnostic algorithms of childhood TB.

Breakthrough of chemiluminescence-based LAM urine test beyond HIV-positive individuals: Clinical diagnostic value of pulmonary tuberculosis in the general population.

To investigate the diagnostic value of a novel high-sensitivity urine lipoarabinomannan (LAM) test (chemiluminescence-based) for active tuberculosis in the general population. A retrospective study was conducted on 250 clinical suspected tuberculosis patients who were HIV-negative and visited the Fourth People's Hospital of Foshan from January 2022 to December 2022. Among them, there were 135 cases of pulmonary tuberculosis, 34 cases of extrapulmonary tuberculosis, and 81 cases of non-tuberculosis. Urine samples were collected for LAM antigen detection before treatment, and laboratory data of sputum smear acid-fast staining (smear method), sputum culture, and GeneXpert method were collected. Using clinical diagnosis as the reference standard, the diagnostic efficacy of 4 methods for detecting active tuberculosis was evaluated. For the 135 cases of pulmonary tuberculosis, the sensitivity of sputum smears, sputm culture, sputm GeneXpert method, and urine LAM were 29.6% (40/135), 45.9% (62/135), 59.3% (80/135), and 51.9% (70/135), respectively. The combination of LAM + GeneXpert and LAM + culture had the highest sensitivity for detecting active pulmonary tuberculosis, which were 71.0% and 78.2%, respectively. For the detection of sputum culture-negative pulmonary tuberculosis, the positive rates of smear, GeneXpert, and LAM were 0.0% (0/73), 53.4% (39/73), and 52.1% (38/73), respectively. LAM + smear and LAM + Genexpert could detect 52.1% and 68.5% of sputum culture-negative patients, respectively. The high-sensitivity urine LAM test holds promise for tuberculosis diagnosis in the general population. It demonstrates high-sensitivity, enabling the detection of sputum culture-negative pulmonary tuberculosis patients. Furthermore, when combined with existing methods, it can enhance the overall detection rate.

Prevalence of Histoplasma Antigenuria among Outpatient Cohort with Advanced HIV in Kampala, Uganda.

In sub-Saharan Africa, an estimated 25% of people with HIV present with advanced HIV and are at high risk of opportunistic infections. Whereas histoplasmosis has occasionally been seen in Uganda, the understanding of the local risk of acute infection is limited. We sought to determine the prevalence of Histoplasma antigenuria using an enzyme immunoassay (EIA, clarus Histoplasma GM EIA, IMMY; Norman, OK, USA) in a cohort of outpatients with advanced HIV disease in Kampala, Uganda. Among the persons with positive urine Histoplasma antigen tests, we assessed their clinical presentation and outcomes. The EIA was run on stored urine samples as per the manufacturer's instructions. Specimens ≥1 EIA units were considered positive. Among the 388 tested urine samples, 4 (1.2%) were positive for Histoplasma antigen. The histoplasmosis prevalence among participants with a CD4 < 100 cells/mcL was 2.5% (4/158). Three of the four participants with a positive Histoplasma antigen test reported systemic symptoms consistent with histoplasmosis. All four participants had a positive urine lipoarabinomannan test and were treated for tuberculosis. By the four-week follow-up visit, all participants were clinically improved, alive, and in care without antifungal therapy. In advanced HIV, the clinical presentations of tuberculosis and histoplasmosis overlap. The value of histoplasmosis screening and pre-emptive treatment is an area of future research.

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

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. 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. 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. 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. FIND, the Global Alliance for Diagnostics.

Роль биомаркеров мочи в диагностике туберкулеза легких (обзор)

Diagnosis of tuberculosis (TB) based on sputum analysis has limitations for certain categories of patients (older adults, children, and people living with HIV). An alternative approach is a non-invasive urine-based method, which provides a large sample volume and a quick result. We searched for English-language publications from 2010 to 2021 in PubMed and Cochrane databases using the terms tuberculosis + urine + biomarkers. Papers on urine lipoarabinomannan testing were excluded as this topic has been sufficiently studied elsewhere. The reviewed publications cover more than 30 urine biomarkers used to diagnose TB and evaluate treatment effectiveness. Urine transrenal DNA extraction continues to be investigated, although its diagnostic sensitivity and specificity depend on the extraction method and patient’s HIV status. IP-10 is likely to be a non-specific inflammatory marker; however, its level correlates with TB/HIV status and may be useful for assessing TB treatment response. Further, the article shows the potential of metabolomic biomarkers and biosignatures for measuring the activity of TB infection and distinguishing it from other respiratory diseases. The number of reliable biomarkers predicting TB treatment outcomes is limited. Numerous untargeted studies have used mass spectrometry to detect metabolomic and proteomic biomarkers in urine. The publications are heterogeneous in design and methods; few studies have analysed the specificity and sensitivity of the diagnostic methods covered. In future, a combination of host and pathogen biomarkers could increase the sensitivity and specificity of TB diagnosis.

High Performance of Systematic Combined Urine Liboarabinomannan Test and Sputum Xpert MTB/RIF for Tuberculosis Screening in Severely Immunosuppressed Ambulatory Adults With Human Immunodeficiency Virus.

In people with human immunodeficiency virus (PWH), the World Health Organization-recommended tuberculosis (TB) 4-symptom screen (W4SS) targeting those who need molecular rapid testing may be suboptimal. We assessed the performance of different TB screening approaches in severely immunosuppressed PWH enrolled in the guided-treatment group of the STATIS trial (NCT02057796). Ambulatory PWH with no overt evidence of TB and CD4 count <100 cells/µL were screened for TB prior to antiretroviral therapy (ART) initiation with W4SS, chest radiograph (CXR), urine lipoarabinomannan (LAM) test, and sputum Xpert MTB/RIF (Xpert). Correctly and wrongly identified cases by screening approaches were assessed overall and by CD4 count threshold (≤50 and 51-99 cells/µL). Of 525 enrolled participants (median CD4 count, 28 cells/µL), 48 (9.9%) were diagnosed with TB at enrollment. Among participants with a negative W4SS, 16% had either a positive Xpert, a CXR suggestive of TB, or a positive urine LAM test. The combination of sputum Xpert and urine LAM test was associated with the highest proportion of participants correctly identified as TB (95.8%) and non-TB cases (95.4%), with proportions equally high among participants with CD4 counts above or below 50 cells/µL. Restricting the use of sputum Xpert, urine LAM test, or CXR to participants with a positive W4SS reduced the proportion of wrongly and correctly identified cases. There is a clear benefit to perform both sputum Xpert and urine LAM tests as TB screening in all severely immunosuppressed PWH prior to ART initiation, not only in those with a positive W4SS. Clinical Trials Registration. NCT02057796.

Performance of novel antibodies for lipoarabinomannan to develop diagnostic tests for Mycobacterium tuberculosis.

Lipoarabinomannan (LAM), a component of the Mycobacterium tuberculosis (MTB) cell wall, is detectable in the urine of MTB infected patients with active tuberculosis (TB). LAM-specific antibodies (Igs) have been developed by a variety of traditional and recombinant methods for potential use in a rapid diagnostic test (RDT). We evaluated the analytical performance of the TB LAM Igs to identify pairs that offer superior performance over existing urine LAM tests. We assessed 25 new and 4 existing Igs in a matrixed format using a multiplex electrochemiluminescence-based liquid immunoassay. A total of 841 paired Ig combinations were challenged with in vitro cultured LAM (cLAM) derived from MTB strains representing diverse phylogenetic lineages, alongside urinary LAM (uLAM) from the urine of adults with active pulmonary TB. Analytical sensitivity of down-selected Ig pairs was determined using MTB Aoyama-B cLAM, while diagnostic accuracy was determined using clinical samples. When testing cLAM, the reactivity of Ig pairs was similar across MTB lineages 1–4 but lineage 5:6 had significantly more reactivity among Ig pairs. Overall, 41 Ig pairs had a strong binding affinity to cLAM, as compared to the reference pair of S4-20/A194-01, and 28 Ig pairs therein exhibited a strong affinity for both cLAM and uLAM. Retrospective testing on clinical urine specimens demonstrated varying sensitivities (12–80%) and specificities (14–100%). The five top pairs had a similar analytical limit of detection to the reference pair but in four instances, the sensitivity and specificity with clinical uLAM samples was poor. Overall, epitopes presented by uLAM are different from cLAM, which may affect antibody performance when testing uLAM in patient samples. Several new Ig pairs had similar ranges of high sensitivity to cLAM but overall, there were no new candidate Ig pairs identified in this round of screening with increased performance with uLAM as compared to an existing optimal pair.

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.

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

BackgroundThe 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. ObjectiveThis study aimed to evaluate the accuracy of urine LAM tests using FujiLAM® for diagnosing EPTB in patients with HIV. MethodsA 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. ResultsAmong 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%). ConclusionThe FujiLAM® test is a feasible method for diagnosing EPTB in patients with HIV.

Xpert Ultra testing of blood in severe HIV-associated tuberculosis to detect and measure Mycobacterium tuberculosis blood stream infection: a diagnostic and disease biomarker cohort study

SummaryBackgroundMycobacterium tuberculosis bloodstream infection is a leading cause of death in people living with HIV and disseminated bacillary load might be a key driver of disease severity. We aimed to assess Xpert MTB/RIF Ultra (Xpert Ultra) testing of blood as a diagnostic for M tuberculosis bloodstream infection and investigate cycle threshold as a quantitative disease biomarker.MethodsIn this cohort study, we obtained biobanked blood samples from a large and well characterised cohort of adult patients admitted to hospital in Western Cape, South Africa with suspected HIV-associated tuberculosis and a CD4 count less than 350 cells per μL. Patients already receiving antituberculosis therapy were excluded. Samples were obtained on recruitment within 72 h of admission to hospital, and patients were followed up for 12 weeks to determine survival. We tested the biobanked blood samples using the Xpert Ultra platform after lysis and wash processing of the blood. We assessed diagnostic yield (proportion of cases detected, with unavailable test results coded as negative) against a microbiological reference, both as a function of markers of critical-illness and compared with other rapid diagnostics (urine lipoarabinomannan and sputum Xpert). Quantitative blood Xpert Ultra results were evaluated as a disease biomarker by assessing association with disease phenotype defined by principal component analysis of 32 host-response markers. Prognostic value compared to other tuberculosis biomarkers was assessed using likelihood ratio testing of nested models predicting 12-week mortality.FindingsBetween Jan 16, 2014, and Oct 19, 2016, of the 659 participants recruited to the parent study, 582 had an available biobanked blood sample. 447 (77%) of 582 met the microbiological reference standard for tuberculosis diagnosis. Median CD4 count was 62 (IQR 221–33) cells per μL, and 123 (21%) of participants died by 12-weeks follow-up. Blood Xpert Ultra was positive in 165 (37%) of 447 participants with confirmed tuberculosis by the microbiological reference standard, with a diagnostic yield of 0·37 (95% CI 0·32–0·42). Diagnostic yield increased with lower CD4 count or haemoglobin, and outperformed urine lipoarabinomannan testing in participants with elevated venous lactate. Quantitative blood Xpert Ultra results were more closely associated with mortality than other tuberculosis biomarkers including blood culture, and urine lipoarabinomannan, or urine Xpert (all p<0·05). A principal component of clinical phenotype capturing markers of inflammation, tissue damage, and organ dysfunction was strongly associated with both blood Xpert-Ultra positivity (associated with a SD increase of 1·1 in PC score, p<0·0001) and cycle threshold (r= −0·5; p<0·0001).InterpretationXpert Ultra testing of pre-processed blood could be used as a rapid diagnostic test in critically ill patients with suspected HIV-associated tuberculosis, while also giving additional prognostic information compared with other available markers. A dose–response relationship between quantitative blood Xpert Ultra results, host-response phenotype, and mortality risk adds to evidence that suggests M tuberculosis bloodstream infection bacillary load is causally related to outcomes.FundingWellcome Trust, National Institute of Health Fogarty International Center, South African MRC, UK National Institute of Health Research, National Research Foundation of South Africa.TranslationsFor the Xhosa and Afrikaans translations of the abstract see Supplementary Materials section.

Diagnostic Accuracy of Urine Lipoarabinomannan Testing in Early Morning Urine versus Spot Urine for Diagnosis of Tuberculosis among People with HIV.

ABSTRACTThe Fujifilm SILVAMP TB LAM (FujiLAM) assay offers improved sensitivity compared to Determine TB LAM Ag (AlereLAM) for detecting tuberculosis (TB) among people with HIV. Here, we examined the diagnostic value of FujiLAM testing on early morning urine versus spot urine and the added value of a two-sample strategy. We assessed the diagnostic accuracy of FujiLAM on cryopreserved urine samples collected and stored as part of a prospective cohort of adults with HIV presenting for antiretroviral treatment in Ghana. We compared FujiLAM sensitivity and specificity in spontaneously voided urine samples collected at inclusion (spot urine) versus in the first voided early morning urine (morning urine) and for a one (spot urine) versus two samples (spot and morning urine) strategy. Diagnostic accuracy was determined against both microbiological (using sputum culture and Xpert MTB/RIF testing of sputum and urine to confirm TB) and composite reference standards (including microbiologically confirmed and probable TB cases). Paired urine samples of spot and morning urine were available for 389 patients. Patients had a median CD4 cell count of 176 cells/μL (interquartile range [IQR], 52 to 361). Forty-three (11.0%) had confirmed TB, and 19 (4.9%) had probable TB. Overall agreement for spot versus morning urine test results was 94.6% (kappa, 0.81). Compared to a microbiological reference standard, the FujiLAM sensitivity (95% confidence interval [CI]) was 67.4% (51.5 to 80.9) for spot and 69.8% (53.9 to 82.8) for morning urine, an absolute difference (95% CI) of 2.4% (−10.2 to 14.8). Specificity was 90.2% (86.5 to 93.1) versus 89.0% (85.2 to 92.1) for spot and morning urine, respectively, a difference of 1.2% (−3.7 to 1.4). A two-sample strategy increased FujiLAM sensitivity from 67.4% (51.5 to 80.9) to 74.4% (58.8 to 86.5), a difference of 7.0% (−3.0 to 16.9), while specificity decreased from 90.2% (86.5 to 93.1) to 87.3% (83.3 to 90.6), a difference of −2.9% (−4.9 to −0.8). This study indicates that FujiLAM testing performs equivalently on spot and early morning urine samples. Sensitivity could be increased with a two-sample strategy but at the risk of lower specificity. These data can inform future guidelines and clinical practice.IMPORTANCE This study indicates that FujiLAM testing performs equivalently on spot and early morning urine samples for detecting tuberculosis among people with HIV. Sensitivity could be increased with a two-sample strategy but at the risk of lower specificity. These data can inform future guidelines and clinical practice around FujiLAM.

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

ObjectivesEven 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 methodsFour 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.ResultsBased 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.ConclusionsUrine 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.

Clinical, radiological, and laboratory predictors of a positive urine lipoarabinomannan test in sputum-scarce and sputum-negative patients with HIV-associated tuberculosis in two Johannesburg hospitals.

BackgroundTuberculosis (TB) is a major cause of mortality in persons living with HIV (PLWH). Sputum-based diagnosis of TB in patients with low CD4 counts is hampered by paucibacillary disease and consequent sputum scarcity or negative sputum results. Urine lipoarabinomannan (LAM) has shown promise in the point-of-care detection of TB in this patient subset but lacks sensitivity, and its exact role in a diagnostic algorithm for TB in South Africa remains to be clarified.ObjectivesThe objective of this study was to better define the patient profile and the TB characteristics associated with a positive urine LAM (LAM+ve) test.MethodThis multicentre retrospective record review examined the clinical, radiological, and laboratory characteristics of hospitalised PLWH receiving urine LAM testing with sputum-scarce and/or negative sputum GeneXpert ® (mycobacterium tuberculosis/resistance to rifampicin [MTB/RIF]) results.ResultsMore than a third of patients, 121/342 (35%), were LAM+ve. The positive yield was greater in the sputum-scarce than the sputum-negative group, 66/156 (42%) versus 55/186 (30%), P = 0.0141, respectively. Patients who were LAM+ve were more likely to be confused (odds ratio [OR] = 2.2, 95% confidence interval [CI] = 1.2–3.7, P = 0.0045), have a higher median heart rate (P = 0.0135) and an elevated quick sepsis-related organ failure assessment score (≥ 2), OR = 3.5, 95% CI = 1.6–7.6, P = 0.0014. A LAM+ve test was significantly associated with disseminated TB (dTB), P < 0.0001, TB-related immune reconstitution inflammatory syndrome (IRIS), P = 0.0035, and abdominal TB, P < 0.0001. Laboratory predictors of a LAM+ve status included renal dysfunction, P = 0.044, severe anaemia, P = 0.0116, and an elevated C-reactive protein, P = 0.0131. Of the 12 PLWH with disseminated non-TB mycobacteria cultured from the blood and/or bone marrow, n = 9 (75%) had a LAM+ve result (OR = 5.8, 95% CI = 1.6–20.8, P = 0.0053).ConclusionUrine LAM testing of hospitalised PLWH with suspected active TB had significant diagnostic utility in those that were sputum-scarce or sputum-negative. A LAM+ve result was associated with dTB, clinical and laboratory markers of severe illness, and TB-IRIS. Disseminated non-tuberculous mycobacterial infection of hospitalised PLWH may also yield urine LAM+ve results, and mycobacterial cultures must be checked in those non-responsive to conventional TB treatment. Selective use of the LAM test in the critically ill is likely to maximise the diagnostic yield, improve the test’s predictive value, and reduce the time to TB diagnosis and initiation of treatment.

Urine Lipoarabinomannan Testing in Adults With Advanced Human Immunodeficiency Virus in a Trial of Empiric Tuberculosis Therapy.

BackgroundThe urine lipoarabinomannan (LAM) antigen test is a tuberculosis (TB) diagnostic test with highest sensitivity in individuals with advanced human immunodeficiency virus (HIV). Its role in TB diagnostic algorithms for HIV-positive outpatients remains unclear.MethodsThe AIDS Clinical Trials Group (ACTG) A5274 trial demonstrated that empiric TB therapy did not improve 24-week survival compared to isoniazid preventive therapy (IPT) in TB screen–negative HIV-positive adults initiating antiretroviral therapy with CD4 counts <50 cells/µL. Retrospective LAM testing was performed on stored urine obtained at baseline. We determined the proportion of LAM-positive participants and conducted modified intent-to-treat analysis excluding LAM-positive participants to determine the effect on 24-week survival, TB incidence, and time to TB using Kaplan-Meier method.ResultsA5274 enrolled 850 participants; 53% were male and the median CD4 count was 18 (interquartile range, 9–32) cells/µL. Of the 850, 566 (67%) had LAM testing (283 per arm); 28 (5%) were positive (21 [7%] and 7 [2%] in the empiric and IPT arms, respectively). Of those LAM-positive, 1 participant in each arm died and 5 of 21 and 0 of 7 in empiric and IPT arms, respectively, developed TB. After excluding these 28 cases, there were 19 and 21 deaths in the empiric and IPT arms, respectively (P = .88). TB incidence remained higher (4.6% vs 2%, P = .04) and time to TB remained faster in the empiric arm (P = .04).ConclusionsAmong outpatients with advanced HIV who screened negative for TB by clinical symptoms, microscopy, and Xpert testing, LAM testing identified an additional 5% of individuals with TB. Positive LAM results did not change mortality or TB incidence.

Xpert-Ultra to Detect and Quantify HIV-Associated &lt;i&gt;Mycobacterium tuberculosis&lt;/i&gt; Blood Stream Infection: A Cohort Study

Background: Mycobacterium tuberculosis bloodstream infection (MTBBSI) is a leading cause of death in people living with HIV. Tools to rapidly identify and quantify MTBBSI could facilitate both diagnosis and research for this critical condition. Methods: We developed a method to detect M. tuberculosis in blood using lysis-wash steps and the Xpert MTB/RIF Ultra platform, testing it on biobanked blood from participants hospitalized with HIV-associated TB. We assessed diagnostic yield (proportion of cases detected, with unavailable test results coded as negative) against a microbiological reference, both as a function of markers of critical-illness and compared with other rapid-diagnostics. Quantitative blood Xpert-Ultra results were evaluated as a disease biomarker by assessing association with disease phenotype defined by principal component analysis of 32 host-response markers, and prognostic value compared to other tuberculosis biomarkers models to predict 12-week mortality. Findings: Of 582 participants, 447 (77%) had tuberculosis; 165 out of 447 were blood Xpert-Ultra positive giving diagnostic yield 0·37 (95%CI 0·32 to 0·42). Diagnostic yield increased with lower CD4 cell count or haemoglobin, and outperformed urine lipoarabinomannan testing in participants with elevated venous lactate. Quantitative blood Xpert-Ultra results predicted mortality better than other tuberculosis biomarkers including blood culture, and urine lipoarabinomannan or urine-Xpert. Both blood Xpert-Ultra positivity and cycle threshold were strongly associated with a principal component of clinical phenotype capturing markers of inflammation, tissue damage and organ dysfunction. Interpretation: Xpert-Ultra testing of pre-processed blood could be used as a rapid diagnostic test in critically ill patients with suspected HIV-associated tuberculosis, while also giving additional prognostic information compared with other available markers. A dose-response relationship between quantitative blood Xpert-Ultra results, host-response phenotype, and mortality risk adds to evidence that suggests MTBBSI bacillary load is causally related to outcomes. Funding Information: Wellcome Trust, Fogarty International Center, South African MRC, NIHR(UK), National Research Foundation of South Africa. Declaration of Interests: All authors declare no conflict of interest. Ethics Approval Statement: This study was approved by the University of Cape Town Human Research Ethics Committee (HREC 057/2013).

Urine Lipoarabinomannan Testing for All HIV Patients Hospitalized in Medical Wards Identifies a Large Proportion of Patients With Tuberculosis at Risk of Death.

BackgroundDiagnosing tuberculosis (TB), the leading cause of death in people with HIV, remains a challenge in resource-limited countries. We assessed TB diagnosis using a strategy that included systematic urine lipoarabinomannan (LAM) testing for all HIV patients hospitalized in medical wards and 6-month mortality according to LAM results.MethodsThis prospective, observational study included adult HIV patients hospitalized in the medical wards of a public district hospital in Malawi regardless of their TB symptoms or CD4 count. Each patient had a clinical examination, and Alere Determine TB-LAM, sputum microscopy, sputum GeneXpert MTB/RIF (Xpert), chest x-ray, and CD4 count were systematically requested.ResultsAmong 387 inpatients, 54% had a CD4 <200 cells/µL, 64% had presumptive TB, and 90% had ≥1 TB symptom recorded in their medical file. LAM results were available for 99.0% of patients, microscopy for 62.8%, and Xpert for 60.7%. In total, 26.1% (100/383) had LAM-positive results, 48% (48/100) of which were grades 2–4. Any TB laboratory test result was positive in 30.8% (119/387). Among patients with no Xpert result, 28.5% (43/151) were LAM-positive. Cumulative 6-month mortality was 40.1% (151/377): 50.5% (49/97) in LAM-positives and 36.2% (100/276) in LAM-negatives (P = .013). In multivariable regression analyses, LAM-positive patients had a higher risk of mortality than LAM-negatives (adjusted odds ratio, 2.5; 95% CI, 1.1–5.8; P = .037).ConclusionsIn resource-limited hospital medical wards with high TB prevalence, a diagnostic strategy including systematic urine LAM testing for all HIV patients is an easily implementable strategy that identifies a large proportion of patients with TB at risk of death.

Urine lipoarabinomannan as a marker for low-risk of NTM infection in the CF airway

BackgroundIndividuals with Cystic fibrosis (CF) are the most vulnerable population for pulmonary infection with nontuberculous mycobacteria (NTM). Screening, diagnosis, and assessment of treatment response currently depend on traditional culture techniques, but sputum analysis for NTM in CF is challenging, and associated with a low sensitivity. The cell wall lipoarabinomannan (LAM), a lipoglycan found in all mycobacterial species, and has been validated as a biomarker in urine for active Mycobacterium tuberculosis infection. MethodsUrine from a CF cohort (n = 44) well-characterized for NTM infection status by airway cultures was analyzed for LAM by gas chromatography/mass spectrometry. All subjects with positive sputum cultures for NTM had varying amounts of LAM in their urine. No LAM was detected in subjects who never had a positive culture (14/45). One individual initially classified as NTM sputum negative subsequently developed NTM disease 657 days after the initial urine LAM testing. Repeat urine LAM testing turned positive, correlating to her positive NTM status. Subjects infected with subspecies of M. abscessus had greater LAM quantities than those infected with M. avium complex (MAC). There was no correlation with disease activity or treatment status and LAM quantity. A TB Capture ELISA using anti-LAM antibodies demonstrated very poor sensitivity in identifying individuals with positive NTM sputum cultures. ConclusionThese findings support the conclusion that urine LAM related to NTM infection may be a useful screening test to determine patients at low risk for having a positive NTM sputum culture, as part of a lifetime screening strategy in the CF population.

Mycobacterium tuberculosis bloodstream infection prevalence, diagnosis, and mortality risk in seriously ill adults with HIV: a systematic review and meta-analysis of individual patient data

SummaryBackgroundThe clinical and epidemiological significance of HIV-associated Mycobacterium tuberculosis bloodstream infection (BSI) is incompletely understood. We hypothesised that M tuberculosis BSI prevalence has been underestimated, that it independently predicts death, and that sputum Xpert MTB/RIF has suboptimal diagnostic yield for M tuberculosis BSI.MethodsWe did a systematic review and individual patient data (IPD) meta-analysis of studies performing routine mycobacterial blood culture in a prospectively defined patient population of people with HIV aged 13 years or older. Studies were identified through searching PubMed and Scopus up to Nov 10, 2018, without language or date restrictions and through manual review of reference lists. Risk of bias in the included studies was assessed with an adapted QUADAS-2 framework. IPD were requested for all identified studies and subject to harmonised inclusion criteria: age 13 years or older, HIV positivity, available CD4 cell count, a valid mycobacterial blood culture result (excluding patients with missing data from lost or contaminated blood cultures), and meeting WHO definitions for suspected tuberculosis (presence of screening symptom). Predicted probabilities of M tuberculosis BSI from mixed-effects modelling were used to estimate prevalence. Estimates of diagnostic yield of sputum testing with Xpert (or culture if Xpert was unavailable) and of urine lipoarabinomannan (LAM) testing for M tuberculosis BSI were obtained by two-level random-effect meta-analysis. Estimates of mortality associated with M tuberculosis BSI were obtained by mixed-effect Cox proportional-hazard modelling and of effect of treatment delay on mortality by propensity-score analysis. This study is registered with PROSPERO, number 42016050022.FindingsWe identified 23 datasets for inclusion (20 published and three unpublished at time of search) and obtained IPD from 20, representing 96·2% of eligible IPD. Risk of bias for the included studies was assessed to be generally low except for on the patient selection domain, which was moderate in most studies. 5751 patients met harmonised IPD-level inclusion criteria. Technical factors such as number of blood cultures done, timing of blood cultures relative to blood sampling, and patient factors such as inpatient setting and CD4 cell count, explained significant heterogeneity between primary studies. The predicted probability of M tuberculosis BSI in hospital inpatients with HIV-associated tuberculosis, WHO danger signs, and a CD4 count of 76 cells per μL (the median for the cohort) was 45% (95% CI 38–52). The diagnostic yield of sputum in patients with M tuberculosis BSI was 77% (95% CI 63–87), increasing to 89% (80–94) when combined with urine LAM testing. Presence of M tuberculosis BSI compared with its absence in patients with HIV-associated tuberculosis increased risk of death before 30 days (adjusted hazard ratio 2·48, 95% CI 2·05–3·08) but not after 30 days (1·25, 0·84–2·49). In a propensity-score matched cohort of participants with HIV-associated tuberculosis (n=630), mortality increased in patients with M tuberculosis BSI who had a delay in anti-tuberculosis treatment of longer than 4 days compared with those who had no delay (odds ratio 3·15, 95% CI 1·16–8·84).InterpretationIn critically ill adults with HIV-tuberculosis, M tuberculosis BSI is a frequent manifestation of tuberculosis and predicts mortality within 30 days. Improved diagnostic yield in patients with M tuberculosis BSI could be achieved through combined use of sputum Xpert and urine LAM. Anti-tuberculosis treatment delay might increase the risk of mortality in these patients.FundingThis study was supported by 10.13039/100010269Wellcome fellowships 109105Z/15/A and 105165/Z/14/A.