Evaluation of a novel point-of-care cryptococcal antigen test on serum, plasma, and urine from patients with HIV-associated cryptococcal meningitis

Diagnostic Performances of an in-House Immunochromatography Test Based on the Monoclonal Antibody 18B7 to Glucuronoxylomannan for Clinical Suspected Cryptococcosis: a Large-Scale Prototype Evaluation in Northern Thailand

OBJECTIVE

Cryptococcosis predominantly presents as a meningoencephalitis in Thailand. Early and expeditious diagnosis is essential for reducing both mortality and morbidity associated with cryptococcal meningitis. We aim to define and establish the diagnostic performances between the benchmark commercially available diagnostic kit (CrAg® LFA) and the large-scale prototype of an inexpensive in-house immunochromatographic test (ICT) based on monoclonal antibody (MAb) 18B7.

METHODS

We have developed the large-scale prototype for the rapid detection of cryptococcal polysaccharide antigens by utilizing a single antibody sandwich ICT format employing MAb 18B7, which is highly specific to Cryptococcus neoformans glucuronoxylomannan (GXM) antigens. An in-house MAb18B7 ICT was manufactured in accordance with industry standards under the control of the International Organization for Standardization (ISO) 13485.

RESULTS

The diagnostic sensitivity, specificity, and accuracy for the in-house MAb 18B7 ICT were 99.10%, 97.61%, and 97.83%, respectively. The agreement kappa (κ) coefficient was 0.968 based on the retrospective evaluation of 580 specimens from patients living in northern Thailand with clinically suspected cryptococcosis.

CONCLUSION

The data suggest that this in-house MAb 18B7 ICT will be highly beneficial for addressing the issue of cryptococcal infection in Thailand. Moreover, it is anticipated that this inexpensive ICT can play a pivotal role in various global strategies aimed at eradicating cryptococcal meningitis among individuals living with HIV by 2030.

Pneumocystis jirovecii pneumonia in people living with HIV: a review

Pneumocystis jirovecii is a ubiquitous opportunistic fungus that can cause life-threatening pneumonia. People with HIV (PWH) who have low CD4 counts are one of the populations at the greatest risk of Pneumocystis jirovecii pneumonia (PCP). While guidelines have approached the diagnosis, prophylaxis, and management of PCP, the numerous studies of PCP in PWH are dominated by the 1980s and 1990s. As such, most studies have included younger male populations, despite PCP affecting both sexes and a broad age range. Many studies have been small and observational in nature, with an overall lack of randomized controlled trials. In many jurisdictions, and especially in low- and middle-income countries, the diagnosis can be challenging due to lack of access to advanced and/or invasive diagnostics. Worldwide, most patients will be treated with 21 days of high-dose trimethoprim sulfamethoxazole, although both the dose and the duration are primarily based on historical practice. Whether treatment with a lower dose is as effective and less toxic is gaining interest based on observational studies. Similarly, a 21-day tapering regimen of prednisone is used for patients with more severe disease, yet other doses, other steroids, or shorter durations of treatment with corticosteroids have not been evaluated. Now with the widespread availability of antiretroviral therapy, improved and less invasive PCP diagnostic techniques, and interest in novel treatment strategies, this review consolidates the scientific body of literature on the diagnosis and management of PCP in PWH, as well as identifies areas in need of more study and thoughtfully designed clinical trials.

Diagnosis and management of cryptococcal meningitis in HIV-infected adults

Cryptococcal meningitis is a leading cause of morbidity and mortality globally, especially in people with advanced HIV disease. Cryptococcal meningitis is responsible for nearly 20% of all deaths related to advanced HIV disease, with the burden of disease predominantly experienced by people in resource-limited countries. Major advancements in diagnostics have introduced low-cost, easy-to-use antigen tests with remarkably high sensitivity and specificity. These tests have led to improved diagnostic accuracy and are essential for screening campaigns to reduce the burden of cryptococcosis. In the last 5 years, several high-quality, multisite clinical trials have led to innovations in therapeutics that have allowed for simplified regimens, which are better tolerated and result in less intensive monitoring and management of medication adverse effects. One trial found that a shorter, 7-day course of deoxycholate amphotericin B is as effective as the longer 14-day course and that flucytosine is an essential partner drug for reducing mortality in the acute phase of disease. Single-dose liposomal amphotericin B has also been found to be as effective as a 7-day course of deoxycholate amphotericin B. These findings have allowed for simpler and safer treatment regimens that also reduce the burden on the healthcare system. This review provides a detailed discussion of the latest evidence guiding the clinical management and special circumstances that make cryptococcal meningitis uniquely difficult to treat.

Clinical and Metagenomic Characterization of Neurological Infections of People With Human Immunodeficiency Virus in the Peruvian Amazon

Background

Neurological opportunistic infections cause significant morbidity and mortality in people with human immunodeficiency virus (HIV) but are difficult to diagnose.

Methods

One hundred forty people with HIV with acute neurological symptoms from Iquitos, Peru, were evaluated for cerebral toxoplasmosis with quantitative polymerase chain reaction (qPCR) of cerebrospinal fluid (CSF) and for cryptococcal meningitis with cryptococcal antigen test (CrAg) in serum or CSF. Differences between groups were assessed with standard statistical methods. A subset of samples was evaluated by metagenomic next-generation sequencing (mNGS) of CSF to compare standard diagnostics and identify additional diagnoses.

Results

Twenty-seven participants were diagnosed with cerebral toxoplasmosis by qPCR and 13 with cryptococcal meningitis by CrAg. Compared to participants without cerebral toxoplasmosis, abnormal Glasgow Coma Scale score (P = .05), unilateral focal motor signs (P = .01), positive Babinski reflex (P = .01), and multiple lesions on head computed tomography (CT) (P = .002) were associated with cerebral toxoplasmosis. Photophobia (P = .03) and absence of lesions on head CT (P = .02) were associated with cryptococcal meningitis. mNGS of 42 samples identified 8 cases of cerebral toxoplasmosis, 7 cases of cryptococcal meningitis, 5 possible cases of tuberculous meningitis, and incidental detections of hepatitis B virus (n = 1) and pegivirus (n = 1). mNGS had a positive percentage agreement of 71% and a negative percentage agreement of 91% with qPCR for T gondii. mNGS had a sensitivity of 78% and specificity of 100% for Cryptococcus diagnosis.

Conclusions

An infection was diagnosed by any method in only 34% of participants, demonstrating the challenges of diagnosing neurological opportunistic infections in this population and highlighting the need for broader, more sensitive diagnostic tests for central nervous system infections.

The SSS revolution in fungal diagnostics: speed, simplicity and sensitivity

INTRODUCTION

Fungal disease has historically presented a diagnostic challenge due to its often non-specific clinical presentations, relative infrequency and reliance on insensitive and time-intensive fungal culture.

SOURCES OF DATA

We present the recent developments in fungal diagnostics in the fields of serological and molecular diagnosis for the most clinically relevant pathogens; developments that have the potential to revolutionize fungal diagnosis through improvements in speed, simplicity and sensitivity. We have drawn on a body of evidence including recent studies and reviews demonstrating the effectiveness of antigen and antibody detection and polymerase chain reaction (PCR) in patients with and without concurrent human immunodeficiency virus infection.

AREAS OF AGREEMENT

This includes recently developed fungal lateral flow assays, which have a low cost and operator skill requirement that give them great applicability to low-resource settings. Antigen detection for Cryptococcus, Histoplasma and Aspergillus spp. are much more sensitive than culture. PCR for Candida spp., Aspergillus spp., Mucorales and Pneumocystis jirovecii is more sensitive than culture and usually faster.

AREAS OF CONTROVERSY

Effort must be made to utilize recent developments in fungal diagnostics in clinical settings outside of specialist centres and integrate their use into standard medical practice. Given the clinical similarities of the conditions and frequent co-infection, further study is required into the use of serological and molecular fungal tests, particularly in patients being treated for tuberculosis.

GROWING POINTS

Further study is needed to clarify the utility of these tests in low-resource settings confounded by a high prevalence of tuberculosis.

AREAS TIMELY FOR DEVELOPING RESEARCH

The diagnostic utility of these tests may require revision of laboratory work flows, care pathways and clinical and lab coordination, especially for any facility caring for the immunosuppressed, critically ill or those with chronic chest conditions, in whom fungal disease is common and underappreciated.

Resolving the Temporal Splenic Proteome during Fungal Infection for Discovery of Putative Dual Perspective Biomarker Signatures

Fungal pathogens are emerging threats to global health with the rise of incidence associated with climate change and increased geographical distribution; factors also influencing host susceptibility to infection. Accurate detection and diagnosis of fungal infections is paramount to offer rapid and effective therapeutic options. For improved diagnostics, the discovery and development of protein biomarkers presents a promising avenue; however, this approach requires a priori knowledge of infection hallmarks. To uncover putative novel biomarkers of disease, profiling of the host immune response and pathogen virulence factor production is indispensable. In this study, we use mass-spectrometry-based proteomics to resolve the temporal proteome of Cryptococcus neoformans infection of the spleen following a murine model of infection. Dual perspective proteome profiling defines global remodeling of the host over a time course of infection, confirming activation of immune associated proteins in response to fungal invasion. Conversely, pathogen proteomes detect well-characterized C. neoformans virulence determinants, along with novel mapped patterns of pathogenesis during the progression of disease. Together, our innovative systematic approach confirms immune protection against fungal pathogens and explores the discovery of putative biomarker signatures from complementary biological systems to monitor the presence and progression of cryptococcal disease.

Preemptive Therapy in Cryptococcosis Adjusted for Outcomes

Cryptococcosis is one of the most serious opportunistic diseases in patients living with HIV. For this reason, early diagnosis and appropriate treatment are important.

OBJECTIVES

The aim of the study was to understand the development of patients diagnosed with cryptococcosis by detection of Cryptococcus antigen in serum by lateral flow assay (CrAg LFA) without nervous system involvement and with treatment in accordance with the results.

MATERIALS AND METHODS

A retrospective, longitudinal, analytical study was performed. Seventy patients with cryptococcosis initially diagnosed by serum CrAg LFA without meningeal involvement between January 2019 and April 2022 were analyzed for medical records. The treatment regimen was adapted to the results of blood culture, respiratory material, and pulmonary tomography imaging.

RESULTS

Seventy patients were included, 13 had probable pulmonary cryptococcosis, 4 had proven pulmonary cryptococcosis, 3 had fungemia, and 50 had preemptive therapy without microbiological or imaging findings compatible with cryptococcosis. Among the 50 patients with preemptive therapy, none had meningeal involvement or cryptococcosis recurrences to date.

CONCLUSION

Preemptive therapy avoided progression to meningitis in CrAg LFA-positive patients. Preemptive therapy with dose adjustment of fluconazole in patients with the mentioned characteristics was useful despite the use of lower doses than recommended.

Cryptococcus neoformans, a global threat to human health

BACKGROUND

Emerging fungal pathogens pose important threats to global public health. The World Health Organization has responded to the rising threat of traditionally neglected fungal infections by developing a Fungal Priority Pathogens List (FPPL). Taking the highest-ranked fungal pathogen in the FPPL, Cryptococcus neoformans, as a paradigm, we review progress made over the past two decades on its global burden, its clinical manifestation and management of cryptococcal infection, and its antifungal resistance. The purpose of this review is to drive research efforts to improve future diagnoses, therapies, and interventions associated with fungal infections.

METHODS

We first reviewed trends in the global burden of HIV-associated cryptococcal infection, mainly based on a series of systematic studies. We next conducted scoping reviews in accordance with the guidelines described in the Preferred Reporting Items for Systematic Reviews and Meta-analyses extension for Scoping Reviews using PubMed and ScienceDirect with the keyword Cryptococcus neoformans to identify case reports of cryptococcal infections published since 2000. We then reviewed recent updates on the diagnosis and antifungal treatment of cryptococcal infections. Finally, we summarized knowledge regarding the resistance and tolerance of C. neoformans to approved antifungal drugs.

RESULTS

There has been a general reduction in the estimated global burden of HIV-associated cryptococcal meningitis since 2009, probably due to improvements in highly active antiretroviral therapies. However, cryptococcal meningitis still accounts for 19% of AIDS-related deaths annually. The incidences of CM in Europe and North America and the Latin America region have increased by approximately two-fold since 2009, while other regions showed either reduced or stable numbers of cases. Unfortunately, diagnostic and treatment options for cryptococcal infections are limited, and emerging antifungal resistance exacerbates the public health burden.

CONCLUSION

The rising threat of C. neoformans is compounded by accumulating evidence for its ability to infect immunocompetent individuals and the emergence of antifungal-resistant variants. Emphasis should be placed on further understanding the mechanisms of pathogenicity and of antifungal resistance and tolerance. The development of novel management strategies through the identification of new drug targets and the discovery and optimization of new and existing diagnostics and therapeutics are key to reducing the health burden.

Point-of-Care Testing for the Diagnosis of Fungal Infections

Invasive fungal infections are increasing worldwide due to factors such as climate change and immunomodulating therapies. Unfortunately, the detection of these infections is limited due to the low sensitivity and long periods required for laboratory testing. Point-of-care testing could lead to more rapid diagnosis of these often devasting infections. However, there are currently no true point-of-care tests on the market for the detection of fungi. In this article, the current state of fungal antigen and molecular testing is reviewed, with commentary on the potential for development and use in the point-of-care setting.

False-negative cerebral spinal fluid cryptococcal antigen lateral flow assay due to postzone phenomenon in a patient with disseminated cryptococcal disease: a case report

This report presents the case of false-negative cerebral spinal fluid (CSF) cryptococcal antigen (CrAg) lateral flow assay (LFA) in a HIV-positive 25-year-old male. The patient presented with headache, nausea and vomiting for 5 days and syncope for 1 day. An initial CSF CrAg LFA test was negative, but a 1:4 dilution of the CSF was weakly positive and a 1:8 dilution was positive. A serum cryptococcal antigen test was weakly positive. Cultures of blood and CSF were all positive for Cryptococcus neoformans. The explanation for the false-negative CSF CrAg LFA test is that the antigen concentration was too high causing the postzone phenomenon.

Assessment of Urinary Biomarkers for Infectious Diseases Using Lateral Flow Assays: A Comprehensive Overview

Screening of biomarkers is a powerful approach for providing a holistic view of the disease spectrum and facilitating the diagnosis and prognosis of the state of infectious diseases. Unaffected by the homeostasis mechanism in the human body, urine accommodates systemic changes and reflects the pathophysiological condition of an individual. Easy availability in large volumes and non-invasive sample collection have rendered urine an ideal source of biomarkers for various diseases. Infectious diseases may be communicable, and therefore early diagnosis and treatment are of immense importance. Current diagnostic approaches preclude the timely identification of clinical conditions and also lack portability. Point-of-care (POC) testing solutions have gained attention as alternative diagnostic measures due to their ability to provide rapid and on-site results. Lateral flow assays (LFAs) are the mainstay in POC device development and have attracted interest owing to their potential to provide instantaneous results in resource-limited settings. The discovery and optimization of a definitive biomarker can render POC testing an excellent platform, thus impacting unwarranted antibiotic administration and preventing the spread of infectious diseases. This Review summarizes the importance of urine as an emerging biological fluid in infectious disease research and diagnosis in clinical settings. We review the academic research related to LFAs. Further, we also describe commercial POC devices based on the identification of urinary biomarkers as diagnostic targets for infectious diseases. We also discuss the future use of LFAs in developing more effective POC tests for urinary biomarkers of various infections.

Comparison of a Prototype SARS-CoV-2 Lateral Flow IMMUNOASSAY with the BinaxNOWTM COVID-19 Antigen CARD

Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) is the virus responsible for the COVID-19 pandemic. From the onset of the pandemic, rapid antigen tests have quickly proved themselves to be an accurate and accessible diagnostic platform. The initial (and still most commonly used antigen tests) for COVID-19 diagnosis were constructed using monoclonal antibodies (mAbs) specific to severe acute respiratory syndrome coronavirus (SARS-CoV) nucleocapsid protein (NP). These mAbs are able to bind SARS-CoV-2 NP due to high homology between the two viruses. However, since first being identified in 2019, SARS-CoV-2 has continuously mutated, and a multitude of variants have appeared. These mutations have an elevated risk of leading to possible diagnostic escape when using tests produced with SARS-CoV-derived mAbs. Here, we established a library of 18 mAbs specific to SARS-CoV-2 NP and used two of these mAbs (1CV7 and 1CV14) to generate a prototype antigen-detection lateral flow immunoassay (LFI). A side-by-side analysis of the 1CV7/1CV14 LFI and the commercially available BinaxNOW^TM COVID-19 Antigen CARD was performed. Results indicated the 1CV7/1CV14 LFI outperformed the BinaxNOW^TM test in the detection of BA.2, BA.2.12.1, and BA.5 Omicron sub-variants when testing remnant RT-PCR positive patient nasopharyngeal swabs diluted in viral transport media.

Cryptococcus neoformans Infection in the Central Nervous System: The Battle between Host and Pathogen

Cryptococcus neoformans (C. neoformans) is a pathogenic fungus with a global distribution. Humans become infected by inhaling the fungus from the environment, and the fungus initially colonizes the lungs. If the immune system fails to contain C. neoformans in the lungs, the fungus can disseminate to the blood and invade the central nervous system, resulting in fatal meningoencephalitis particularly in immunocompromised individuals including HIV/AIDS patients. Following brain invasion, C. neoformans will encounter host defenses involving resident as well as recruited immune cells in the brain. To overcome host defenses, C. neoformans possesses multiple virulence factors capable of modulating immune responses. The outcome of the interactions between the host and C. neoformans will determine the disease progression. In this review, we describe the current understanding of how C. neoformans migrates to the brain across the blood–brain barrier, and how the host immune system responds to the invading organism in the brain. We will also discuss the virulence factors that C. neoformans uses to modulate host immune responses.

Immunologic Diagnosis of Endemic Mycoses

The endemic mycoses blastomycosis, coccidioidomycosis, histoplasmosis, paracoccidioidomycosis, cryptococcosis, sporotrichosis, talaromycosis, adiaspiromycosis, and emergomycosis are mostly caused by geographically limited thermally dimorphic fungi (except for cryptococcosis), and their diagnoses can be challenging. Usual laboratory methods involved in endemic mycoses diagnosis include microscopic examination and culture of biological samples; however, serologic, histopathologic, and molecular techniques have been implemented in the last few years for the diagnosis of these mycoses since the recovery and identification of their etiologic agents is time-consuming and lacks in sensitivity. In this review, we focus on the immunologic diagnostic methods related to antibody and antigen detection since their evidence is presumptive diagnosis, and in some mycoses, such as cryptococcosis, it is definitive diagnosis.

Diagnostic Accuracy of Point of Care Cryptococcal Antigen Lateral Flow Assay in Fingerprick Whole Blood and Urine Samples for the Detection of Asymptomatic Cryptococcal Disease in Patients with Advanced HIV Disease

Cryptococcal disease (CD) is a leading cause of mortality among individuals with advanced HIV disease (AHD). Screening with serum cryptococcal antigen (sCrAg) lateral flow assay (LFA) enables early detection of subclinical disease but requires venipuncture and laboratory processing. Clinic-based point of care (POC) CrAg screening tests using urine or fingerprick whole blood could facilitate early diagnosis of CD. We evaluated the diagnostic performance of POC clinic-based fingerprick whole blood and urine CrAg compared to the gold standard laboratory sCrAg LFA in screening for CD among asymptomatic individuals with CD4 counts of <200 cells/μL in Harare, Zimbabwe. sCrAg positive participants who consented to a lumbar puncture also had cerebrospinal fluid (CSF) CrAg testing and titers for CSF-positive specimens. A total of 1,333 individuals were screened, and over half (56.6%) were males. The median (interquartile range) CD4 count was 27.5 (11–46) cells/μL. We found a sensitivity of 63.8% (95% CI: 54.8–72.1) and specificity of 84.0% (95% CI: 81.7–86.0) for urine CrAg, and a sensitivity of 48.0% (95% CI: 39.1–57.1) and specificity of 99.5% (95% CI: 98.9–99.8) was found for fingerprick whole blood. The sensitivity of both POC CrAg tests increased in individuals with sCrAg titers of ≥1:160, CD4 count of <50 cells/μL and disseminated central nervous system (CNS) disease. Clinic-based POC urine and fingerprick whole blood CrAg testing performed better in screening for CD among AHD patients with CNS disease. More sensitive assays to identify AHD patients with asymptomatic CD are needed.

IMPORTANCE Cryptococcal disease (CD) remains a leading cause of morbidity and mortality among individuals with advanced HIV disease (AHD). Identifying point of care (POC) approaches to screening for CD in asymptomatic individuals is important to guide therapeutic management. We evaluated the use of POC fingerprick whole blood and urine testing for cryptococcal disease in patients with AHD as compared with laboratory-based serum antigen testing. POC fingerprick whole blood and urine testing had low sensitivity and specificity in asymptomatic individuals with AHD. Most analysis has focused on evaluating test performance in symptomatic individuals. Here we show that POC testing with whole blood and urine samples should not be used to screen for asymptomatic CD in AHD.

Glycosylated gold nanoparticles in point of care diagnostics: from aggregation to lateral flow

Current point-of-care lateral flow immunoassays, such as the home pregnancy test, rely on proteins as detection units (e.g. antibodies) to sense for analytes. Glycans play a fundamental role in biological signalling and recognition events such as pathogen adhesion and hence they are promising future alternatives to antibody-based biosensing and diagnostics. Here we introduce the potential of glycans coupled to gold nanoparticles as recognition agents for lateral flow diagnostics. We first introduce the concept of lateral flow, including a case study of lateral flow use in the field compared to other diagnostic tools. We then introduce glycosylated materials, the affinity gains achieved by the cluster glycoside effect and the current use of these in aggregation based assays. Finally, the potential role of glycans in lateral flow are explained, and examples of their successful use given.

Antibody-based lateral flow (immune) assays are well established, but here the emerging concept and potential of using glycans as the detection agents is reviewed.

Rapid urine-based screening tests increase the yield of same-day tuberculosis diagnoses among patients living with advanced HIV disease

OBJECTIVE

Investigation of the diagnostic yield of urine-based tuberculosis (TB) screening in patients with advanced HIV disease.

DESIGN

A cross-sectional screening study.

SETTING

HIV outpatient clinics and wards at two hospitals in Johannesburg, South Africa, between June 2015 and October 2017.

PARTICIPANTS

Two hundred and one patients living with advanced HIV disease (CD4+ T-lymphocytes <100 cells/μl) attending healthcare facilities following cryptococcal antigen (CrAg) screening.

INTERVENTION

Screening for TB using sputum for microscopy, culture, and Xpert MTB/Rif and urine for lipoarabinomannan (LAM) and Xpert Ultra.

MAIN OUTCOME MEASURES

Proportion of positive results using each testing modality, sensitivity, and specificity of urine-based testing compared with culture, and survival outcomes during 6 months follow up.

RESULTS

Urine was obtained from 177 of 181 (98%) participants and sputum from 91 (50%). Urine-based screening increased same-day diagnostic yield from 7 (4%) to 31 (17%). A positive urine test with either LAM or Xpert Ultra had 100% sensitivity (95% confidence interval, 59-100%) for detecting culture-positive TB at any site. Patients with newly diagnosed TB on urine-based screening were initiated on treatment and did not have excess mortality compared with the remainder of the cohort.

CONCLUSION

Urine is an easily obtainable sample with utility for detecting TB in patients with advanced HIV disease. Combining urine and sputum-based screening in this population facilitates additional same-day TB diagnoses and early treatment initiation, potentially reducing the risk of TB-related mortality. Urine-based as well as sputum-based screening for TB should be integrated with CrAg screening in patients living with advanced HIV disease.

Transcriptional Profiles Elucidate Differential Host Responses to Infection with Cryptococcus neoformans and Cryptococcus gattii

Many aspects of the host response to invasive cryptococcal infections remain poorly understood. In order to explore the pathobiology of infection with common clinical strains, we infected BALB/cJ mice with Cryptococcus neoformans, Cryptococcus gattii, or sham control, and assayed host transcriptomic responses in peripheral blood. Infection with C. neoformans resulted in markedly greater fungal burden in the CNS than C. gattii, as well as slightly higher fungal burden in the lungs. A total of 389 genes were significantly differentially expressed in response to C. neoformans infection, which mainly clustered into pathways driving immune function, including complement activation and TH2-skewed immune responses. C. neoformans infection demonstrated dramatic up-regulation of complement-driven genes and greater up-regulation of alternatively activated macrophage activity than seen with C gattii. A 27-gene classifier was built, capable of distinguishing cryptococcal infection from animals with bacterial infection due to Staphylococcus aureus with 94% sensitivity and 89% specificity. Top genes from the murine classifiers were also differentially expressed in human PBMCs following infection, suggesting cross-species relevance of these findings. The host response, as manifested in transcriptional profiles, informs our understanding of the pathophysiology of cryptococcal infection and demonstrates promise for contributing to development of novel diagnostic approaches.

End-Functionalized Poly(vinylpyrrolidone) for Ligand Display in Lateral Flow Device Test Lines

Lateral flow devices are rapid (and often low cost) point-of-care diagnostics—the classic example being the home pregnancy test. A test line (the stationary phase) is typically prepared by the physisorption of an antibody, which binds to analytes/antigens such as viruses, toxins, or hormones. However, there is no intrinsic requirement for the detection unit to be an antibody, and incorporating other ligand classes may bring new functionalities or detection capabilities. To enable other (nonprotein) ligands to be deployed in lateral flow devices, they must be physiosorbed to the stationary phase as a conjugate, which currently would be a high-molecular-weight carrier protein, which requires (challenging) chemoselective modifications and purification. Here, we demonstrate that poly(vinylpyrrolidone), PVP, is a candidate for a polymeric, protein-free test line, owing to its unique balance of water solubility (for printing) and adhesion to the nitrocellulose stationary phase. End-functionalized PVPs were prepared by RAFT polymerization, and the model capture ligands of biotin and galactosamine were installed on PVP and subsequently immobilized on nitrocellulose. This polymeric test line was validated in both flow-through and full lateral flow formats using streptavidin and soybean agglutinin and is the first demonstration of an “all-polymer” approach for installation of capture units. This work illustrates the potential of polymeric scaffolds as anchoring agents for small-molecule capture agents in the next generation of robust and modular lateral flow devices and that macromolecular engineering may provide real benefit.

Evaluation of a Cryptococcus Capsular Polysaccharide Detection FungiXpert LFA (Lateral Flow Assay) for the Rapid Diagnosis of Cryptococcosis

Cryptococcus is an opportunistic pathogenic fungus and is the major cause of fungal meningitis. The cryptococcal antigen (CrAg) lateral flow assay (LFA) is an immunochromatographic test system that has simplified diagnosis as a point-of-care test. In this study, we evaluated the diagnostic performance of Cryptococcal capsular polysaccharide detection FungiXpert (Genobio Pharmaceutical, Tianjin, China) using serum and cerebrospinal fluid (CSF) samples for the diagnosis of cryptococcosis and investigated the cross-reaction of the assays to pathogenic fungi and bacterium by comparing it to the U.S. Food and Drug Administration (US FDA)-approved IMMY CrAg LFA. Eighty CSF and 119 serum/plasma samples from 158 patients were retrospectively collected to test for qualitative or semi-quantitative detection of CrAg. Cross-reaction of the assays was tested using 28 fungi and 1 bacterium. Compared to IMMY CrAg LFA, the FungiXpert LFA demonstrated 99.1% sensitivity and 98.9% specificity in the qualitative test. In the 96 semi-quantitative CrAg assay results, 39 (40.6%) test titers of FungiXpert LFA were 1-2 dilutions higher than those of IMMY CrAg LFA. The Intraclass Correlation Coefficient of the Semi-quantitative results of CrAg titer tests via the two assays was 0.976. Similar to IMMY CrAg LFA, FungiXpert LFA showed cross-reactivity with Trichosporon asahii. Compared with the IMMY CrAg LFA, the FungiXpert LFA showed an equal, yet, excellent performance. However, it is important to note that these two assays have potential cross-reactivity to T. asahii when diagnosing patients. FungiXpert LFA is a rapid screening method for the effective and practical diagnosis and treatment of cryptococcosis.

Nasopharyngeal cryptococcosis in a cat: interlaboratory variation in cryptococcal antigen assay test results

Case summary

An indoor-only 6-year-old spayed female domestic cat was evaluated for a history of stertorous respiration. Skull radiographs revealed increased soft tissue density within the caudal aspect of the left nasal cavity. CT and rhinoscopy revealed a mass lesion in the choana, plus a smaller lesion, nearly completely occluding flow through the nasal passages. Rhinoscopy was used to collect a biopsy specimen from a fleshy, tan–yellow mass visualized in the caudal nasopharynx. Histopathology was diagnostic for Cryptococcus species infection and systemic antifungal therapy with fluconazole was initiated. Following a series of discordant results, serum samples were submitted to a veterinary diagnostic laboratory that utilized a cryptococcal antigen latex agglutination system with pretreatment of serum with pronase. Twenty-three months after the initial diagnosis, the cat’s serum cryptococcal antigen titer declined to 1:5 and the cat has responded well to continuing treatment.

Relevance and novel information

This case illustrates challenges associated with discordant test results for cryptococcal antigen among laboratories. Discordancies may be due to differences in assay design, or the underlying disease state itself, or whether serum is pre-treated with pronase; with some tests relying on the training and experience of the operator if the cryptococcal antigen detection test requires a subjective interpretation. It also resolves some confusion in the literature related to the assay types available and terminology used to describe them, and emphasizes the importance of considering cryptococcosis as an important differential for cats with upper respiratory signs, without nasal discharge, even if the cat is kept exclusively indoors.

Development and Application of Rapid Clinical Visualization Molecular Diagnostic Technology for Cryptococcus neoformans/C. gattii Based on Recombinase Polymerase Amplification Combined With a Lateral Flow Strip

Cryptococcus neoformans (C. neoformans)/C. gattii can easily invade the human central nervous system and cause cryptococcal meningitis (CM). The clinical fatality rate of these fungi is extremely high and causes more than 180,000 deaths worldwide every year. At present, the common clinical identification methods of these fungi are traditional culture methods and Indian ink staining. In addition, enzyme-linked immunosorbent assay (ELISAs), polymerase chain reaction (PCR), real-time quantitative PCR detecting system (qPCR), mass spectrometry, and metagenomic next-generation sequencing (mNGS) have also been applied to detect these fungus. Due to the rapid progress of meningitis caused by C. neoformans/C. gattii infection, there is a desperate need for fast, sensitive, and on-site detection methods to meet the clinical diagnosis. Recombinase polymerase amplification (RPA) is a promising isothermal amplification technique that can compensate for the shortcomings of the above techniques, featuring short reaction time, high specificity, and high sensitivity, thus meeting the demand for in-field detection of C.neoformans/C. gattii. In our study, RPA- lateral flow strip (LFS) was used to amplify the capsule-associated gene, CAP64, of C. neoformans/C. gattii, and the primer-probe design was optimized by introducing base mismatches to obtain a specific and sensitive primer-probe combination for clinical testing, and specificity of the detection system was determined for 26 common clinical pathogens. This system was developed to obtain results in 20 min at an isothermal temperature of 37°C with a lower limit of detection as low as 10 CFU/μL or 1 fg/μL. A total of 487 clinical samples collected from multicenter multiplexes were tested to evaluate the detection performance of the RPA-LFS system, which revealed that the system could specifically detect C. neoformans/C. gattii, meeting the need for rapid, specific, and sensitive detection.

Cost-Effectiveness Analysis of the Implementation of Cryptococcal Antigen Lateral Flow Assay for the Diagnosis of Cryptococcal Meningitis in Symptomatic People Living With Human Immunodeficiency Virus in Brazil

OBJECTIVES

Cryptococcal meningitis constitutes a significant source of mortality in the developing world. Annually, approximately 625 000 deaths occur worldwide among patients with human immunodeficiency virus (HIV) infection. This study aims to assess the cost-effectiveness of implementing cryptococcal antigen lateral flow assay (CRAG-LFA) screening in Brazil compared with the current practice.

METHODS

An economic evaluation using a Monte Carlo microsimulation was conducted, considering the perspective of the Brazilian Public Health System, to calculate the cost-effectiveness of 4 diagnosis tests: (1) CRAG-LFA, (2) the cryptococcal antigen latex agglutination (CRAG-LA) test, (3) India ink, and (4) nontracking as a baseline. The time horizon comprised 1 year for the intervention and 5 years for the budgetary impact analysis. Two primary effectiveness outcomes were considered: years of life and quality-adjusted life-years.

RESULTS

CRAG-LFA has extended dominance vis à vis CRAG-LA and India ink. CRAG-LFA would cost $418.46 more than CRAG-LA for the treatment of each symptomatic patient living with HIV, with an incremental cost effectiveness ratio of $2478.75/quality-adjusted life year. The budgetary impact analysis estimated that the incorporation of CRAG-LFA would have an additional cost of $1 959 236.50 in 5 years.

CONCLUSIONS

These findings suggest that, for patients living with HIV in the Brazilian Public Health System, the adoption of CRAG-LFA screening is cost-effective compared with the use of CRAG-LA and India ink. It represents an opportunity to prevent cryptococcal meningitis and its mortality in Brazil.

Evaluation of point of care serum cryptococcal antigen by lateral flow immunoassay for diagnosis of cryptococcosis and cryptococcal meningitis in HIV-positive patients

Background:

Cryptococcal meningitis (CM) is the initial acquired immunodeficiency syndrome (AIDS) defining illness in 2% of patients with CD4 levels <100/μL and a leading cause of mortality in AIDS in the developing world. It is the most common opportunistic infection of the central nervous system in AIDS in various Indian studies. Detection of serum cryptococcal antigen (SCRAG) is the most widely used diagnostic method for cryptococcosis. The presence of cerebrospinal fluid cryptococcal antigen (CSF CRAG) is diagnostic of CM. CRAG can be determined by latex agglutination (LAT), enzyme-linked immunosorbent assay and now, by lateral flow (LFA)immunoassay. LFA is a point of care test that rapidly detects CRAG.

Aims and Objectives:

This study compares LAT and LFA for the detection of serum CRAG and diagnosing CM.

Materials and methods:

Two hundred and ten patients of HIV/AIDS were submitted to SCRAG LFA by dipstick. A sample was also sent to laboratory for SCRAG by LAT. CSF examination was done for those who were positive for SCRAG LFA and those who had symptoms suggestive of meningitis. SCRAG by LFA was compared with SCRAG by LAT, CSF CRAG by LAT and LFA, CSF cryptococcal culture and CSF India ink examination for Cryptococcus.

Results:

Fifteen patients were found positive for SCRAG by LFA dipstick. All of them were also positive for SCRAG by LAT. Twelve of them had C. D4 count below below 100 cells/mm3. CSF CRAG was positive in all 12 SCRAG positive who were submitted to CSF examination.

Conclusion:

We found that serum detection of CRAG by LFA dipstick is as sensitive as CRAG detection in serum by LAT and CSF CRAG detection by LFA and LAT. It is thus a rapid test for diagnosing CM in HIV patients with low CD4 counts.

Symptomatic Cryptococcal Meningitis with Negative Serum and Cerebrospinal Fluid Cryptococcal Antigen Tests

Background

Cryptococcal meningitis is a leading cause of mortality in advanced HIV disease. A positive cerebrospinal fluid cryptococcal antigen (CrAg) test defines cryptococcal meningitis. Herein, we present a patient with serum and cerebrospinal fluid CrAg negative cryptococcal meningitis, despite a positive cerebrospinal fluid India ink examination and quantitative culture.

Case Details

A 56-year-old HIV-positive Ugandan woman, with an undetectable HIV RNA viral load and CD4+ T-cell count of 766 cells per microlitre presented with signs and symptoms consistent with cryptococcal meningitis. Her serum and cerebrospinal fluid CrAg tests were negative despite having a positive cerebrospinal fluid India ink and quantitative culture. On day 1, she was commenced on intravenous amphotericin B deoxycholate (1mg/kg) for 3 days (considering 10 CFU growth of Cryptococcus spp) in combination with oral flucytosine (100mg/kg) for 7 days and then fluconazole 1200mg once daily for the next 11 days. By day 7, she was symptom free and quantitative cerebrospinal fluid culture was negative for Cryptococcus spp. She was discharged on day 9. At 10 weeks (day +40) and 18 weeks (day +72), she was well and adherent to her antiretroviral therapy and on maintenance phase of cryptococcal meningitis on fluconazole at a dose of 400mg once daily.

Conclusion

This report alerts clinicians managing patients with HIV-associated cryptococcal meningitis to four uncommon clinical scenarios; first, the possibility of negative serum and cerebrospinal fluid CrAg lateral flow assay results in the context of low cerebrospinal fluid fungal burden in a symptomatic patient. Second, possible occurrence of cryptococcal meningitis in a patient with high CD4 T-cell lymphocyte counts. Third, an early seroconversion of cryptococcal antigenaemia following effective fluconazole therapy. Fourth, an early symptomatic relapse of cryptococcal meningitis albeit negative serum CrAg.

Point of care tests for invasive fungal infections: a blueprint for increasing availability in Africa

Invasive fungal infections (IFIs) such as cryptococcosis, disseminated histoplasmosis, and chronic pulmonary aspergillosis are significant causes of morbidity and mortality in Africa. Lack of laboratory infrastructure and laboratory personnel trained in diagnostic mycology hamper prompt detection and management of IFIs on the continent. Point-of-care tests (POCT) obviate the need for complex infrastructure, skilled technicians, and stable electricity and have had major impacts on the diagnosis of bacterial, viral, and parasitic infections in low- and middle-income countries. Over the last 10 years, POCTs for IFIs have become increasingly available and they have the potential to revolutionize the management of these infections if scaled up in Africa. At the beginning of 2021, the World Health Organization (WHO) Essential Diagnostic List (EDL) included a cryptococcal antigen test for the diagnosis of cryptococcosis, Histoplasma antigen test for the diagnosis of disseminated histoplasmosis, and Aspergillus-specific test for the diagnosis of chronic pulmonary aspergillosis. All of these are available in formats that may be used as POCTs and it is hoped that this will improve the diagnosis of these life-threatening IFIs, especially in low- and middle-income countries. This perspective review discusses commercially available POCTs and outlines strategies of a blueprint to achieve their roll-out in Africa. The strategies include raising awareness, conducting research that uncovers the exact burden of IFIs, increasing advocacy, integrating diagnosis of IFIs into existing public health programs, adoption of the WHO EDL at country levels, and improving logistics and supply chains.

Laboratory Reflex and Clinic-Based Point-of-Care Cryptococcal Antigen Screening for Preventing Meningitis and Mortality Among People Living With HIV

INTRODUCTION

Cryptococcosis remains a leading cause of meningitis and mortality among people living with HIV (PLHIV) worldwide. We sought to evaluate laboratory-based cryptococcal antigen (CrAg) reflex testing and a clinic-based point-of-care (POC) CrAg screening intervention for preventing meningitis and mortality among PLHIV in South Africa.

METHODS

We conducted a prospective pre-post intervention study of adults presenting for HIV testing in Umlazi township, South Africa, over a 6-year period (2013-2019). Participants were enrolled during 3 phases of CrAg testing: CrAg testing ordered by a clinician (clinician-directed testing, 2013-2015); routine laboratory-based CrAg reflex testing for blood samples with CD4 ≤100 cells/mm3 (laboratory reflex testing, 2015-2017); and a clinic-based intervention with POC CD4 testing and POC CrAg testing for PLHIV with CD4 ≤200 cells/mm3 with continued standard-of-care routine laboratory reflex testing among those with CD4 ≤100 cells/mm3 (clinic-based testing, 2017-2019). The laboratory and clinical teams performed serum CrAg by enzyme immunoassay and lateral flow assay (Immy Diagnostics, Norman, OK). We followed up participants for up to 14 months to compare associations between baseline CrAg positivity, antiretroviral therapy and fluconazole treatment initiation, and outcomes of cryptococcal meningitis, hospitalization, and mortality.

RESULTS

Three thousand one hundred five (39.4%) of 7877 people screened were HIV-positive, of whom 908 had CD4 ≤200 cells/mm3 and were included in the analyses. Laboratory reflex and clinic-based testing increased CrAg screening (P < 0.001) and diagnosis of CrAg-positive PLHIV (P = 0.011). When compared with clinician-directed testing, clinic-based CrAg testing showed an increase in the number of PLHIV diagnosed with cryptococcal meningitis (4.5% vs. 1.5%; P = 0.059), initiation of fluconazole preemptive therapy (7.2% vs. 2.5%; P = 0.010), and initiation of antiretroviral therapy (96.8% vs. 91.3%; P = 0.012). Comparing clinic-based testing with laboratory reflex testing, there was no significant difference in the cumulative incidence of cryptococcal meningitis (4.5% vs. 4.1%; P = 0.836) or mortality (8.1% vs. 9.9%; P = 0.557).

CONCLUSIONS

Laboratory reflex and clinic-based CrAg testing facilitated the diagnosis of HIV-associated cryptococcosis and fluconazole initiation but did not reduce cryptococcal meningitis or mortality. In this nonrandomized cohort, clinical outcomes were similar between laboratory reflex testing and clinic-based POC CrAg testing.

Recognition of Diagnostic Gaps for Laboratory Diagnosis of Fungal Diseases: Expert Opinion from the Fungal Diagnostics Laboratories Consortium (FDLC)

Fungal infections are a rising threat to our immunocompromised patient population, as well as other nonimmunocompromised patients with various medical conditions. However, little progress has been made in the past decade to improve fungal diagnostics. To jointly address this diagnostic challenge, the Fungal Diagnostics Laboratory Consortium (FDLC) was recently created. The FDLC consists of 26 laboratories from the United States and Canada that routinely provide fungal diagnostic services for patient care. A survey of fungal diagnostic capacity among the 26 members of the FDLC was recently completed, identifying the following diagnostic gaps: lack of molecular detection of mucormycosis; lack of an optimal diagnostic algorithm incorporating fungal biomarkers and molecular tools for early and accurate diagnosis of Pneumocystis pneumonia, aspergillosis, candidemia, and endemic mycoses; lack of a standardized molecular approach to identify fungal pathogens directly in formalin-fixed paraffin-embedded tissues; lack of robust databases to enhance mold identification with matrix-assisted laser desorption/ionization time-of-flight mass spectrometry; suboptimal diagnostic approaches for mold blood cultures, tissue culture processing for Mucorales, and fungal respiratory cultures for cystic fibrosis patients; inadequate capacity for fungal point-of-care testing to detect and identify new, emerging or underrecognized, rare, or uncommon fungal pathogens; and performance of antifungal susceptibility testing. In this commentary, the FDLC delineates the most pressing unmet diagnostic needs and provides expert opinion on how to fulfill them. Most importantly, the FDLC provides a robust laboratory network to tackle these diagnostic gaps and ultimately to improve and enhance the clinical laboratory's capability to rapidly and accurately diagnose fungal infections.

An inexpensive point-of-care immunochromatographic test for Talaromyces marneffei infection based on the yeast phase specific monoclonal antibody 4D1 and Galanthus nivalis agglutinin

Talaromyces marneffei is a thermally dimorphic fungus that causes opportunistic systemic mycoses in patients with AIDS or other immunodeficiency syndromes. The purpose of this study was to develop an immunochromatographic strip test (ICT) based on a solid phase sandwich format immunoassay for the detection of T. marneffei antigens in clinical urine specimens. The T. marneffei yeast phase specific monoclonal antibody 4D1 (MAb4D1) conjugated with colloidal gold nanoparticle was used as a specific signal reporter. Galanthus nivalis Agglutinin (GNA) was adsorbed onto nitrocellulose membrane to serve as the test line. Similarly, a control line was created above the test line by immobilization of rabbit anti-mouse IgG. The immobilized GNA served as capturing molecule and as non-immune mediated anti-terminal mannose of T. marneffei antigenic mannoprotein. The MAb4D1–GNA based ICT showed specific binding activity with yeast phase antigen of T. marneffei, and it did not react with other common pathogenic fungal antigens. The limit of detection of this ICT for T. marneffei antigen spiked in normal urine was approximately 0.6 μg/ml. The diagnostic performance of the ICT was validated using 341 urine samples from patents with culture- confirmed T. marneffei infection and from a control group of healthy individuals and patients with other infections in an endemic area. The ICT exhibited 89.47% sensitivity, 100% specificity, and 97.65% accuracy. Our results demonstrate that the urine-based GNA–MAb4D1 based ICT produces a visual result within 30 minutes and that the test is highly specific for the diagnosis of T. marneffei infection. The findings validate the deployment of the ICT for clinical use.

Talaromycosis (Penicilliosis marneffei) is a neglected disease that causes an opportunistic systemic mycoses in AIDS and other immune-deficient patients living in Southeast Asia, China and the Indian subcontinent. Although laboratory culture remains a gold standard diagnostic method, it lacks sensitivity and is time-consuming, which results in delayed patient’s treatment and needed care. In this study, we develop an immunochromatographic strip test (ICT) by utilizing a yeast phase specific monoclonal antibody 4D1 and Galanthus nivalis agglutinin for detection of T. marneffei antigens in clinical urine specimens. Our data showed that the assay exhibited high sensitivity (89.47%) and specificity (100%), with its result available within 30 minutes. In addition, this diagnostic assay is inexpensive, reproducible, and simple to perform. Therefore, the T. marneffei ICT should be considered for clinical application in the context of rapid and affordable point-of-care diagnostic test to reduce the burden of talaromycosis mortality in patients in low resource countries.

A Novel, Inexpensive In-House Immunochromatographic Strip Test for Cryptococcosis Based on the Cryptococcal Glucuronoxylomannan Specific Monoclonal Antibody 18B7

The aim of this study was to develop a novel lateral flow immunochromatoghaphic strip test (ICT) for detecting cryptococcal polysaccharide capsular antigens using only a single specific monoclonal antibody, mAb 18B7. The mAb 18B7 is a well characterized antibody that specifically binds repeating epitopes displayed on the cryptococcal polysaccharide glucuronoxylomannan (GXM). We validated the immunoreactivities of mAb 18B7 against capsular antigens of different cryptococcal serotypes. The mAb 18B7 ICT was constructed as a sandwich ICT strip and the antibody serving in the mobile phase (colloidal gold conjugated mAb 18B7) to bind one of the GXM epitopes while the stationary phase antibody (immobilized mAb18B7 on test line) binding to other remaining unoccupied epitopes to generate a positive visual readout. The lower limit of detection of capsular antigens for each of the Cryptococcus serotypes tested was 0.63 ng/mL. No cross-reaction was found against a panel of antigens isolated from cultures of other pathogenic fungal, except the crude antigen of Trichosporon sp. with the lower limit of detection of 500 ng/mL (~800 times higher than that for cryptococcal GXM). The performance of the mAb 18B7 ICT strip was studied using cerebrospinal fluid (CSF) and serum and compared to commercial diagnostic kits (latex agglutination CALAS and CrAg IMMY). The sensitivity, specificity and accuracy of the mAb18B7 ICT with CSF from patients with confirmed cryptococcal meningitis were 92.86%, 100% and 96.23%, respectively. No false positives were observed with samples from non-cryptococcosis patients. With serum samples, the mAb 18B7 ICT gave a sensitivity, specificity and accuracy of 96.15%, 97.78% and 96.91%, respectively. Our results show that the mAb 18B7 based ICT was reliable, reproducible, and cost-effective as a point-of-care immunodiagnostic test for cryptococcosis. The mAb 18B7 ICT may be particularly useful in countries where commercial kits are not available or affordable.

Evaluation of a Cryptococcal Antigen Lateral Flow Assay and Cryptococcal Antigen Positivity at a Large Public Hospital in Atlanta, Georgia

BACKGROUND

Cryptococcus neoformans is a major cause of morbidity and mortality among human immunodeficiency virus (HIV)-infected persons worldwide, and there are scarce recent data on cryptococcal antigen (CrAg) positivity in the United States We sought to determine the frequency of cryptococcal disease and compare the performance of a CrAg lateral flow assay (LFA) versus latex agglutination (LA) test.

METHODS

All patients from Grady Health System in Atlanta who had a serum or cerebrospinal fluid (CSF) sample sent for CrAg testing as part of clinical care from November 2017 to July 2018 were included. Percentage positivity and test agreement were calculated.

RESULTS

Among 467 patients, 557 diagnostic tests were performed; 413 on serum and 144 on CSF. The mean age was 44 years, and most were male (69%) and had HIV (79%). Twenty-four (6.4%, 95% confidence interval [CI] = 4.1-9.4) patients were serum CrAg positive, and 8 (5.8%, 95% CI = 2.6-11.2) individuals tested positive for CSF CrAg. Although overall agreement between the LA and LFA was substantial to high for CSF (κ = 0.71, 95% CI = 0.51-0.91) and serum (κ = 0.93, 95% CI = 0.86-1.00), respectively, there were important discrepancies. Five patients had false-positive CSF LA tests that affected clinical care, and 4 patients had discordant serum tests.

CONCLUSIONS

We found a moderately high proportion of cryptococcal disease and important discrepancies between the LA test and LFA. Clinical implications of these findings include accurate detection of serum CrAg and averting unnecessary treatment of meningitis with costly medications associated with high rates of adverse events.

One Health aspects & priority roadmap for fungal diseases : A mini-review

Fungal diseases have not been taken seriously in public health agendas as well as research priorities, despite of globally causing an estimated two million deaths every year, and the emergence of many troublesome fungal pathogens like Candida auris, azole resistant Aspergillus fumigatus, terbinafine and azole resistant dermatophytes, and zoonotic sporotrichosis in humans. Fungi are also responsible for huge losses of agricultural products and stored crops as well as recent massive and unexpected mortality in animals caused by white-nose syndrome in the bats and Chytridiomycosis in amphibians. This review aims to underscore the need for collaborative, multisectoral, and trans-disciplinary approach to include the One Health approach as an essential component of surveillance, prevention, and control of globally emerging fungal diseases. Rigorous evidence based surveillance of the environment as well as strengthening rapid and quality diagnosis of fungal diseases can save millions of lives and reduce significant morbidity.

Clinical features and prognostic analysis of patients with Aspergillus isolation during acute exacerbation of chronic obstructive pulmonary disease

Background

Lower respiratory tract (LRT) specimen culture is widely performed for the identification of Aspergillus. We investigated the clinical features and prognosis of patients with Aspergillus isolation from LRT specimens during acute exacerbation of chronic obstructive pulmonary disease (AECOPD).

Methods

This is a 6-year single-center, real-world study. 75 cases out of 1131 hospitalized AECOPD patients were positive for Aspergillus. These patients were carefully evaluated and finally diagnosed of pulmonary aspergillosis (PA, 60 cases, 80%) or colonization (15 cases, 20%). Comparisons of clinical data were performed between these two groups. A cox regression model was used to confirm prognostic factors of Aspergillus infection.

Results

The PA group had worse lung function and higher rates of systemic corticosteroid use and broad-spectrum antibiotic use before admission than the colonization group. The PA group had significantly higher in-hospital mortality and 180-day mortality than the colonization group (45% (27/60) vs. 0% (0/15), p = 0.001, and 52.5% (31/59) vs. 6.7% (1/15), p < 0.001, respectively). By multivariable analysis among Aspergillus infection patients, antifungal therapy (HR 0.383, 95% CI 0.163–0.899, p = 0.027) was associated with improved survival, whereas accumulated dose of systemic steroids > 700 mg (HR 2.452, 95% CI 1.134–5.300, p = 0.023) and respiratory failure at admission (HR 5.983, 95% CI 2.487–14.397, p < 0.001) were independently associated with increased mortality. Significant survival differential was observed among PA patients without antifungals and antifungals initiated before and after Aspergillus positive culture (p = 0.001).

Conclusions

Aspergillus isolation in hospitalized AECOPD patients largely indicated PA. AECOPD patients with PA had worse prognosis than those with Aspergillus colonization. Empirical antifungal therapy is warranted to improve the prognosis for Aspergillus infection.

Evaluation of the Dynamiker Cryptococcal Antigen Lateral Flow Assay for the Diagnosis of HIV-Associated Cryptococcosis

Cryptococcal meningitis is a leading cause of meningitis in sub-Saharan Africa. Given the need for rapid point-of-care testing, we evaluated the diagnostic performance of the Dynamiker cryptococcal antigen (CrAg) lateral flow assay (LFA). We assessed the diagnostic performance of the Dynamiker CrAg LFA compared to the IMMY CrAg LFA as the reference standard. We tested 150 serum, 115 plasma, and 100 cerebrospinal fluid (CSF) samples from HIV patients with symptomatic meningitis and 113 serum samples from patients with suspected asymptomatic cryptococcal antigenemia. Compared to the IMMY CrAg LFA, sensitivity of Dynamiker CrAg LFA was 98% in serum, 100% in plasma, 100% in CSF from symptomatic patients and 96% in serum from asymptomatic patients. Specificity was 66% in serum, 61% in plasma, and 91% in CSF from symptomatic patients, and 86% in serum from asymptomatic patients. The positive predictive value was 85% in serum, 82% in plasma, and 96% in CSF from symptomatic patients, and 69% in serum from asymptomatic patients. The negative predictive value was 94% in serum, 100% in plasma, and 100% in CSF from symptomatic patients, and 99% in serum from asymptomatic patients. The interassay reproducibility was 100% across the four sample types with no observed discordant results when Dynamiker CrAg LFA was tested in duplicate. However, a high number of false positives were observed on serum of symptomatic patients (11%), serum of asymptomatic patients (11%) and plasma of symptomatic patients (14%). The Dynamiker CrAg LFA had excellent sensitivity but poor specificity, particularly when tested on serum and plasma.

A case-control study of human immunodeficiency virus-negative patients with cryptococcemia and cryptococcal meningitis in a Chinese tertiary care hospital during 10 years

OBJECTIVE

This study aimed to characterize patients with cryptococcemia and compare the clinical features of cryptococcemia and cryptococcal meningitis.

METHODS

This was a retrospective, case-control study. We retrospectively identified blood cultures with Cryptococcus spp. growth. Controls were hospitalized patients who suffered from cryptococcal meningitis, but did not experience cryptococcemia. Controls and cases were matched by admission date, age, sex, and body weight. Clinical information was analyzed by two independent reviewers.

RESULTS

Eight patients with cryptococcemia and eight patients with cryptococcal meningitis were included. They were all negative for human immunodeficiency virus. The most common underlying disease was primary nephrotic syndrome. All patients presented with fever. The incidence of headache, nausea/vomiting, seizures, and cough/expectoration was significantly lower in patients with cryptococcemia than in those with cryptococcal meningitis. All clinical strains of Cryptococcus, except for one, were sensitive to fluconazole, voriconazole, itraconazole, amphotericin B, and flucytosine in vitro. The rate of receiving an amphotericin B-containing regimen was significantly higher in patients with cryptococcal meningitis than in those with cryptococcemia. In-hospital mortality was significantly higher in cryptococcemia cases compared with cryptococcal meningitis cases.

CONCLUSION

Cryptococcemia is an unusual infection characterized by a high mortality. Cryptococcemia requires early identification and prompt antifungal therapy.

Diagnostic Accuracy of the Biosynex CryptoPS Cryptococcal Antigen Semiquantitative Lateral Flow Assay in Patients with Advanced HIV Disease

High cryptococcal antigen (CrAg) titers in blood are associated with subclinical meningitis and mortality in CrAg-positive individuals with advanced HIV disease (AHD). We evaluated a novel semiquantitative lateral flow assay (LFA), CryptoPS, that may be able to identify individuals with high CrAg titers in a cohort of AHD patients undergoing CrAg screening. In a prospective cohort of patients with AHD (CD4 cell count, ≤200/μl) receiving CD4 count testing, whole blood was tested for CrAg by CryptoPS and the IMMY LFA; the two assays were conducted by two different operators, each blind to the results of the other assay.

High cryptococcal antigen (CrAg) titers in blood are associated with subclinical meningitis and mortality in CrAg-positive individuals with advanced HIV disease (AHD). We evaluated a novel semiquantitative lateral flow assay (LFA), CryptoPS, that may be able to identify individuals with high CrAg titers in a cohort of AHD patients undergoing CrAg screening. In a prospective cohort of patients with AHD (CD4 cell count, ≤200/μl) receiving CD4 count testing, whole blood was tested for CrAg by CryptoPS and the IMMY LFA; the two assays were conducted by two different operators, each blind to the results of the other assay. The sensitivity, specificity, positive predictive value (PPV), and negative predictive value (NPV) of CryptoPS were assessed against the IMMY LFA as a reference. CryptoPS low-titer (T1 band) and high-titer (T2 band) results were compared with IMMY LFA titers obtained through serial dilution. A total of 916 specimens were tested. The sensitivity of the CryptoPS assay was 61.0% (25/41) (95% confidence interval [95% CI], 44.5 to 75.8%), its specificity was 96.6% (845/875) (95% CI, 95.1 to 97.7%), its PPV was 45.5% (95% CI, 32.0 to 59.4%), and its NPV was 98.1% (95% CI, 97.0 to 98.9%). All (16/16) CryptoPS false-negative results were obtained for samples with IMMY titers of ≤1:160. Of 29 patients (30 specimens) who tested positive by CryptoPS but negative by the IMMY LFA, none developed cryptococcal meningitis over 3 months of follow-up without fluconazole. Median CrAg titers were 1:20 (interquartile range [IQR], 0 to 1:160) in CryptoPS T1-positive samples and 1:2,560 (IQR, 1:1,280 to 1:10,240) in T2-positive samples. We conclude that the diagnostic accuracy of the CryptoPS assay was suboptimal in the context of CrAg screening, with poor sensitivity at low CrAg titers. However, the CryptoPS assay reliably detected individuals with high titers, which are associated with poor outcomes.

Johnson E, Littlechild J, Winlove CP, Vollmer F, Gow NAR. Biosensors and Diagnostics for Fungal Detection

Early detection is critical to the successful treatment of life-threatening infections caused by fungal pathogens, as late diagnosis of systemic infection almost always equates with a poor prognosis. The field of fungal diagnostics has some tests that are relatively simple, rapid to perform and are potentially suitable at the point of care. However, there are also more complex high-technology methodologies that offer new opportunities regarding the scale and precision of fungal diagnosis, but may be more limited in their portability and affordability. Future developments in this field are increasingly incorporating new technologies provided by the use of new format biosensors. This overview provides a critical review of current fungal diagnostics and the development of new biophysical technologies that are being applied for selective new sensitive fungal biosensors to augment traditional diagnostic methodologies.

Asymptomatic cryptococcal antigenemia in HIV-infected patients: a review of recent studies

The prevalence of asymptomatic cryptococcal antigenemia (ACA) in human immunodeficiency virus (HIV) infected individuals has been observed to be elevated. The prevalence of ACA ranges from 1.3% to 13%, with different rates of prevalence in various regions of the world. We reviewed studies conducted internationally, and also referred to two established expert consensus guideline documents published in China, and we have concluded that Chinese HIV-infected patients should undergo cryptococcal antigen screening when CD4 T-cell counts fall below 200 cells/μL and that the recommended treatment regimen for these patients follow current World Health Organization guidelines, although it is likely that this recommendation may change in the future. Early screening and optimized preemptive treatment for ACA is likely to help decrease the incidence of cryptococcosis, and is lifesaving. Further studies are warranted to explore issues related to the optimal management of ACA.

Diagnosing Pneumocystis jirovecii pneumonia: A review of current methods and novel approaches

Pneumocystis jirovecii can cause life-threatening pneumonia in immunocompromised patients. Traditional diagnostic testing has relied on staining and direct visualization of the life-forms in bronchoalveolar lavage fluid. This method has proven insensitive, and invasive procedures may be needed to obtain adequate samples. Molecular methods of detection such as polymerase chain reaction (PCR), loop-mediated isothermal amplification (LAMP), and antibody-antigen assays have been developed in an effort to solve these problems. These techniques are very sensitive and have the potential to detect Pneumocystis life-forms in noninvasive samples such as sputum, oral washes, nasopharyngeal aspirates, and serum. This review evaluates 100 studies that compare use of various diagnostic tests for Pneumocystis jirovecii pneumonia (PCP) in patient samples. Novel diagnostic methods have been widely used in the research setting but have faced barriers to clinical implementation including: interpretation of low fungal burdens, standardization of techniques, integration into resource-poor settings, poor understanding of the impact of host factors, geographic variations in the organism, heterogeneity of studies, and limited clinician recognition of PCP. Addressing these barriers will require identification of phenotypes that progress to PCP and diagnostic cut-offs for colonization, generation of life-form specific markers, comparison of commercial PCR assays, investigation of cost-effective point of care options, evaluation of host factors such as HIV status that may impact diagnosis, and identification of markers of genetic diversity that may be useful in diagnostic panels. Performing high-quality studies and educating physicians will be crucial to improve the rates of diagnosis of PCP and ultimately to improve patient outcomes.

HIV-associated Cryptococcal Meningitis: a Review of Novel Short-Course and Oral Therapies

Purpose of review

HIV-associated cryptococcal meningitis remains a significant public health problem in parts of Africa and Asia and a major cause of AIDS-related mortality, accounting for 15% of all AIDS-related deaths worldwide. Cryptococcal meningitis is uniformly fatal if untreated, and access to antifungal therapy in regions with the highest burden is often limited. Outcomes with fluconazole monotherapy are poor, and induction treatment with amphotericin B and high-dose fluconazole for 2 weeks is associated with significant drug-related toxicities and prolonged hospital admissions. This review focuses on the potential of novel short-course and oral combination therapies for cryptococcal meningitis.

Recent findings

Recent clinical trials have shown that shorter courses of amphotericin, if paired with oral flucytosine, rather than fluconazole, can achieve non-inferior mortality outcomes. In addition, an oral combination of fluconazole and flucytosine is a potential alternative. Liposomal amphotericin B may further simplify treatment; it is associated with fewer drug-related toxicities, and a recent phase II randomised controlled trial demonstrated that a single, high dose of liposomal amphotericin is non-inferior to 14 standard daily doses at clearing Cryptococcus from cerebrospinal fluid. This has been taken forward to an ongoing phase III, clinical endpoint study.

Summary

The incidence and mortality associated with cryptococcal meningitis is still unacceptably high. There is evidence supporting the use of short-course amphotericin B and oral combination antifungal treatment regimens for cryptococcal meningitis (CM). Ongoing research into short-course, high-dose treatment with liposomal amphotericin may also help reduce the impact of this devastating disease.

False-Negative Serum Cryptococcal Antigen Lateral Flow Immunoassay Result for a Patient with Disseminated Cryptococcal Disease

Cryptococcus neoformans (C. neoformans) is an opportunistic fungal pathogen to humans, which can be acquired from environmental sources. Its most important virulence factor is its polysaccharide capsule, which can be used for diagnostic tests that identify the cryptococcal antigen (CrAg). The CrAg lateral flow assay (LFA) is a dipstick immunochromatographic assay with high sensitivity and specificity; however, several false-negative cases have been reported. Here, we present a case of a false-negative serum CrAg LFA, in which the blood culture from a matched sample was positive for C. neoformans, thus demonstrating the postzone phenomenon.

Evaluation of a Novel Semiquantitative Cryptococcal Antigen Lateral Flow Assay in Patients with Advanced HIV Disease

Higher cryptococcal antigen (CrAg) titers are strongly associated with mortality risk in individuals with HIV-associated cryptococcal disease. Rapid tests to quantify CrAg levels may provide important prognostic information and enable treatment stratification. We performed a laboratory-based validation of the IMMY semiquantitative cryptococcal antigen (CrAgSQ) lateral flow assay (LFA) against the current gold standard CrAg tests. We assessed the diagnostic accuracy of the CrAgSQ in HIV-positive individuals undergoing CrAg screening, determined the relationship between CrAgSQ scores and dilutional CrAg titers, assessed interrater reliability, and determined the clinical correlates of CrAgSQ scores.

Higher cryptococcal antigen (CrAg) titers are strongly associated with mortality risk in individuals with HIV-associated cryptococcal disease. Rapid tests to quantify CrAg levels may provide important prognostic information and enable treatment stratification. We performed a laboratory-based validation of the IMMY semiquantitative cryptococcal antigen (CrAgSQ) lateral flow assay (LFA) against the current gold standard CrAg tests. We assessed the diagnostic accuracy of the CrAgSQ in HIV-positive individuals undergoing CrAg screening, determined the relationship between CrAgSQ scores and dilutional CrAg titers, assessed interrater reliability, and determined the clinical correlates of CrAgSQ scores. A total of 872 plasma samples were tested using both the CrAgSQ LFA and the conventional IMMY CrAg LFA, of which 692 were sequential samples from HIV-positive individuals undergoing CrAg screening and an additional 180 were known CrAg-positive plasma samples archived from prior studies. Interrater agreement in CrAgSQ reading was excellent (98.17% agreement, Cohen’s kappa 0.962, P < 0.001). Using the IMMY CrAg LFA as a reference standard, CrAgSQ was 93.0% sensitive (95% confidence interval [CI] 80.9% to 98.5%) and 93.8% specific (95% CI, 91.7% to 95.6%). After reclassification of discordant results using CrAg enzyme immunoassay testing, the sensitivity was 98.1% (95% CI, 90.1% to 100%) and specificity 95.8% (95% CI, 93.9% to 97.2%). The median CrAg titers for semiquantitative score categories (1+ to 4+) were 1:10 (interquartile range [IQR], 1:5 to 1:20) in the CrAgSQ 1+ category, 1:40 (IQR, 1:20 to 1:80) in the CrAgSQ 2+ category, 1:640 (IQR, 1:160 to 1:2,560) in the CrAgSQ 3+ category, and 1:5,120 (IQR, 1:2,560 to 1:30,720) in the CrAgSQ 4+ category. Increasing CrAgSQ scores were strongly associated with 10-week mortality. The IMMY CrAgSQ test had high sensitivity and specificity compared to the results for the IMMY CrAg LFA and provided CrAg scores that were associated with both conventional CrAg titers and clinical outcomes.

Cryptococcal meningitis: a review of cryptococcal antigen screening programs in Africa

INTRODUCTION

Cryptococcal meningitis remains a significant contributor to AIDS-related mortality despite widened access to antiretroviral therapy. Cryptococcal antigen (CrAg) can be detected in the blood prior to development of meningitis. Development of highly sensitive and specific rapid diagnostic CrAg tests has helped facilitate the adoption of CrAg screening programs in 19 African countries.

AREAS COVERED

The biological rationale for CrAg screening and the programmatic strategies for its implementation are reviewed. We describe the approach to the investigation of patients with cryptococcal antigenemia and the importance of lumbar puncture to identify individuals who may have cryptococcal meningitis in the absence of symptoms. The limitations of current treatment recommendations and the potential role of newly defined combination antifungal therapies are discussed. A literature review was conducted using a broad database search for cryptococcal antigen screening and related terms in published journal articles dating up to December 2019. Conference abstracts, publicly available guidelines, and project descriptions were also incorporated.

EXPERT OPINION

As we learn more about the risks of cryptococcal antigenemia, it has become clear that the current management paradigm is inadequate. More intensive investigation and management are required to prevent the development of cryptococcal meningitis and reduce mortality associated with cryptococcal antigenemia.

Diagnosis and treatment of invasive fungal infections: looking ahead

Improved standards of care depend on the development of new laboratory diagnostic and imaging procedures and the development of new antifungal compounds. Immunochromatography technologies have led to the development of lateral flow devices for the diagnosis of cryptococcal meningitis and invasive aspergillosis (IA). Similar devices are being developed for the detection of histoplasmosis that meet the requirements for speed (∼15 min assay time) and ease of use for point-of-care diagnostics. The evolution of molecular tools for the detection of fungal pathogens has been slow but the introduction of new nucleic acid amplification techniques appears to be helpful, for example T2Candida. An Aspergillus proximity ligation assay has been developed for a rapid near-patient bedside diagnosis of IA. CT remains the cornerstone for radiological diagnosis of invasive pulmonary fungal infections. MRI of the lungs may be performed to avoid radiation exposure. MRI with T2-weighted turbo-spin-echo sequences exhibits sensitivity and specificity approaching that of CT for the diagnosis of invasive pulmonary aspergillosis. The final part of this review looks at new approaches to drug discovery that have yielded new classes with novel mechanisms of action. There are currently two new classes of antifungal drugs in Phase 2 study for systemic invasive fungal disease and one in Phase 1. These new antifungal drugs show promise in meeting unmet needs with oral and intravenous formulations available and some with decreased potential for drug-drug interactions. Novel mechanisms of action mean these agents are not susceptible to the common resistance mechanisms seen in Candida or Aspergillus. Modification of existing antifungal susceptibility testing techniques may be required to incorporate these new compounds.

Comparing immunochromatography with latex antigen agglutination testing for the diagnosis of cryptococcosis in cats, dogs and koalas

Although the point-of-care cryptococcal antigen lateral flow assay (LFA) has revolutionized the diagnosis of cryptococcosis in human patients, to date there has been no large-scale examination of this test in animals. We therefore assessed the LFA in cats, dogs and koalas suspected of having cryptococcosis. In sum, 528 serum specimens (129 from cats, 108 from dogs, 291 from koalas) were tested using the LFA and one of two commercially available latex cryptococcal antigen agglutination test (LCAT) kits. The LCAT is a proven and well-accepted method in veterinary patients and therefore taken as the "gold standard" against which the LFA was compared. The LFA achieved a sensitivity of 92%, 100%, and 98% in cats, dogs, and koalas, respectively, with corresponding negative predictive values of 94%, 100%, and 98%. The specificity of the LFA was 81%, 84%, and 62% for cats, dogs, and koalas, respectively, with corresponding positive predictive values of 76%, 48%, and 69%. These findings suggest the most appropriate role for the LFA is as a screening test to rule out a diagnosis of cryptococcosis in cats, dogs, and koalas. Point-of-care accessibility makes it equally suited for use in the field and as a cage-side test in veterinary hospitals. The suboptimal specificity of the LFA makes it less suited to definitive confirmation of cryptococcosis in animals; therefore, all LFA-positive test results should be confirmed by LCAT testing. The discrepancy between these observations and the high specificity of the LFA in humans may reflect differences in the host-pathogen interactions amongst the species.