Antigen Detection in the Diagnosis of Histoplasmosis: A Meta-analysis of Diagnostic Performance

Identification and production of novel potential pathogen-specific biomarkers for diagnosis of histoplasmosis

IMPORTANCE

Histoplasmosis is considered one of the most important mycoses due to the increasing number of individuals susceptible to develop severe clinical forms, particularly those with HIV/AIDS or receiving immunosuppressive biological therapies, the high mortality rates reported when antifungal treatment is not initiated in a timely manner, and the limitations of conventional diagnostic methods. In this context, there is a clear need to improve the capacity of diagnostic tools to specifically detect the fungal pathogen, regardless of the patient's clinical condition or the presence of other co-infections. The proposed novel pathogen-specific biomarkers have the potential to be used in immunodiagnostic platforms and antifungal treatment monitoring in histoplasmosis. In addition, the bioinformatics strategy used in this study could be applied to identify potential diagnostic biomarkers in other models of fungal infection of public health importance.

The Current and Future States of Diagnostic Tests for Histoplasmosis with a Focus on People with HIV and Disseminated Histoplasmosis

Histoplasmosis is caused by Histoplasma capsulatum and, although endemic in large parts of the world, is often underrecognized in many locations. In addition to underrecognition, inadequate availability of diagnostic tests is a major contributor to poor outcomes in disseminated disease in people with HIV. For those with advanced HIV and disseminated disease, antibody testing is less useful. Culture and histopathology can be useful in this situation, but each has limitations, including variable sensitivity by site and, in the case of culture, the need for a biosafety level three laboratory and a long period of growth. Antigen testing has proven useful for disseminated histoplasmosis due to the excellent sensitivity of urine. Yet, turnaround is slower than ideal due to use in a limited number of centers. The development of lateral flow assays has the potential to make for true rapid point-of-care assays for histoplasmosis, but in order to meet that promise, the tests must be widely available and affordable.

Disseminated Histoplasmosis with Underlying Sarcoidosis-Rheumatoid Arthritis Overlap Syndrome: An Example of Diagnostic Test Threshold of Detection Affecting Test Results and Patient Care

Histoplasmosis is common in many parts of the world but with areas of hyperendemicity. Disseminated histoplasmosis is the deadliest form of histoplasmosis and is most common among immunocompromised patients. Timely diagnosis is crucial to improve outcomes. We describe a patient on azathioprine and rituximab with disseminated histoplasmosis in which diagnosis was delayed in part because of negative early Histoplasma antigen testing, which was positive later in the course. This case serves as an example of the concept of “threshold of detection” in which a certain concentration of a microbe must be present for it to be detected by a diagnostic test that focuses on detection of a microbe or its components. This concept applies to many tests used to diagnose infectious diseases.

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.

Fungal Infection in Lung Transplantation

Invasive fungal infections threaten lung transplant outcomes with high associated morbidity and mortality. Pharmacologic prophylaxis may be key to prevent posttransplant invasive fungal infections, but cost, adverse effects, and absorption issues are barriers to effective prophylaxis. Trends in fungal infection diagnostic strategies utilize molecular diagnostic methodologies to complement traditional histopathology and culture techniques. While lung transplant recipients are susceptible to a variety of fungal pathogens, Candida spp. and Aspergillus spp. infections remain the most common. With emerging resistant organisms and multiple novel antifungal agents in the research pipeline, it is likely that treatment strategies will continue to evolve.

Diagnosis of Pulmonary Infections Due to Endemic Fungi

Endemic mycoses including Histoplasma, Blastomyces, Coccidioides, Paracoccidioides, and Talaromyces are dimorphic fungi that can cause a variety of clinical manifestations, including respiratory infections. Their pulmonary presentations are variable, and diagnosis is often delayed as they can mimic other infectious and non-infectious causes of pulmonary disease. Delay in diagnosis can lead to unnecessary antibiotic use, repeat hospitalizations, and increased morbidity and mortality. The diagnosis of endemic fungal pulmonary infections often relies on multiple diagnostic tests including culture, tissue histopathology, antigen assays, and antibody assays. Due to the increased use of immunosuppressive agents and the widening geographic ranges where these infections are being found, the prevalence of endemic fungal infections is increasing. Physicians need to be aware of the clinical manifestations of pulmonary infections due to endemic fungal in order to ensure that the proper diagnostic work up is obtained promptly. A high index of suspicion is particularly important in patients with suspected pulmonary infections who have failed to improve despite antibiotics in the appropriate setting. We present a review diagnostic testing for pulmonary infections due to endemic mycoses.

An unusual presentation of cutaneous histoplasmosis as a recurrent solitary and spontaneously healing lesion in an immunocompetent patient

Infection with Histoplasma capsulatum typically manifests as a self-limiting pulmonary disease in immunocompetent patients. Systemic symptoms such as cutaneous lesions are associated with immunodeficient states. Our patient was an immunocompetent 68-year-old male who presented with a plaque on his left infraorbital area that was concerning for malignancy. Histological examination of the lesion revealed granulomatous inflammation and small yeast forms suggestive of H. capsulatum. The lesion resolved spontaneously and recurred 1 year later. On recurrence, histological examination again revealed yeast forms consistent with H. capsulatum. Serum and urine testing for H. capsulatum antigen were negative. Next-generation sequencing detected H. capsulatum, which supported the diagnosis of a cutaneous infection. The patient was prescribed and started treatment with itraconazole for 1 year after recurrence of the lesion, and he has not reported further disease recurrence to date. This case is unique because of the presentation of a primary cutaneous recurrent H. capsulatum lesion, and it demonstrated the utility of laboratory testing in its diagnosis.

Advances in the diagnosis of fungal pneumonias

INTRODUCTION

Fungal infections are increasingly encountered in clinical practice due to more favorable environmental conditions and increasing prevalence of immunocompromised individuals. The diagnostic approach for many fungal pathogens continues to evolve. Herein, we outline available diagnostic tests for the most common fungal infections with a focus on recent advances and future directions.

AREAS COVERED

We discuss the diagnostic testing methods for angioinvasive molds (Aspergillus spp. and Mucor spp.), invasive yeast (Candida spp. and Cryptococcus ssp.), Pneumocystis, and endemic fungi (Blastomyces sp., Coccidioides ssp., and Histoplasma sp.). The PubMed-NCBI database was searched within the past 5 years to identify the most recent available literature with dates extended in cases where literature was sparse. Diagnostic guidelines were utilized when available with references reviewed.

EXPERT OPINION

Historically, culture and/or direct visualization of fungal organisms were required for diagnosis of infection. Significant limitations included ability to collect specimens and delayed diagnosis associated with waiting for culture results. Antigen and antibody testing have made great strides in allowing quicker diagnosis of fungal infections but can be limited by low sensitivity/specificity, cross-reactivity with other fungi, and test availability. Molecular methods have a rich history in some fungal diseases, while others continue to be developed.

Improved serodiagnosis of histoplasmosis by use of deglycosylated extracellular released antigens of Histoplasma capsulatum

The diagnosis of histoplasmosis depends on various approaches: direct clinical examination, fungus isolation from cultures of clinical samples, histopathological evaluation, and serological testing. In serodiagnostic assays, the Histoplasma capsulatum H and M antigenic glycoproteins have been extensively used. However, both antigens showed limitations attributed mainly to their cross-reactivity with glycoproteins from other pathogenic fungi, which compromises specificity, and generates false positives, misdiagnosis, and therapeutic failure. In this work, we deglycosylated extracellular released antigens from the Venezuelan 7090 H. capsulatum clinical isolate, using chemical and enzymatic methods and evaluated their effectiveness by indirect enzyme-linked immunosorbent assay (ELISA) with sera from patients with either histoplasmosis or PCM. Prior to deglycosylation, the extracellular released antigen showed 62% of sensitivity 66% of specificity and 68% of cross-reactivity with paracoccidioidomicosis sera. The chemically deglycosylated extracellular released antigen, for 8 or 18  h showed 72 and 52% sensitivity with 98% and 92% specificity, respectively. Moreover, cross-reactivity with Paracoccidioides decreased to 4 and 16%, following deglycosylation for 8 or 18 h, respectively. The enzymatically treated antigen showed 52% of sensitivity, 92% of specificity and 8% cross-reactivity against Paracoccidioides. Deglycosylation of the H. capsulatum antigen improves its specificity and decreases its cross-reactivity against Paracoccidioides when using indirect ELISA for serodiagnosis. Therefore, it is recommended to deglycosylate the fungal extracellular released antigen for clinical serodiagnosis, and to monitor humoral immune responses during therapy of patients with the different clinical forms of histoplasmosis.

Timely Diagnosis of Histoplasmosis in Non-endemic Countries: A Laboratory Challenge

Human histoplasmosis is a fungal infection caused by the inhalation of microconidia of the thermally dimorphic fungi Histoplasma capsulatum. Autochthonous cases of histoplasmosis have been diagnosed in almost every country, but it is considered an endemic infection in specific areas of the world. Many of them are popular travel destinations or the source of migratory movements. Thus, the vast majority of the registered cases in non-endemic countries are imported. They correspond to people having been exposed to the fungus in endemic locations as immigrants, expatriates, transient workers or tourists, with reported cases also associated to organ donation. Misdiagnosis and delays in initiation of treatment are not uncommon in cases of imported histoplasmosis. They are associated to high fatality-rates specially in patients with compromised cellular immunity in which progressive disseminated forms develop. The diagnosis of this infection in non-endemic countries is hampered by the lack of clinical suspicion and a dearth of available diagnostic tools adequate to offer rapid and accurate results. Non-culture-based assays such as nucleic-acid amplification tests present as a suitable alternative in this situation, offering improved sensitivity and specificity, shortened turnaround time, and increased biosafety by avoiding culture manipulation. In non-endemic regions, molecular techniques are being used mainly in laboratories from countries that have registered an increase in the incidence of imported cases. However, the number of published techniques is limited and lack consensus. Efforts are currently under way to standardize nucleic acid amplification-based techniques for its implementation in areas registering a rising number of imported cases.

Microbiological Laboratory Testing in the Diagnosis of Fungal Infections in Pulmonary and Critical Care Practice. An Official American Thoracic Society Clinical Practice Guideline

Background: Fungal infections are of increasing incidence and importance in immunocompromised and immunocompetent patients. Timely diagnosis relies on appropriate use of laboratory testing in susceptible patients.Methods: The relevant literature related to diagnosis of invasive pulmonary aspergillosis, invasive candidiasis, and the common endemic mycoses was systematically reviewed. Meta-analysis was performed when appropriate. Recommendations were developed using the Grading of Recommendations Assessment, Development, and Evaluation approach.Results: This guideline includes specific recommendations on the use of galactomannan testing in serum and BAL and for the diagnosis of invasive pulmonary aspergillosis, the role of PCR in the diagnosis of invasive pulmonary aspergillosis, the role of β-d-glucan assays in the diagnosis of invasive candidiasis, and the application of serology and antigen testing in the diagnosis of the endemic mycoses.Conclusions: Rapid, accurate diagnosis of fungal infections relies on appropriate application of laboratory testing, including antigen testing, serological testing, and PCR-based assays.

Diagnosis of Progressive Disseminated Histoplasmosis in Advanced HIV: A Meta-Analysis of Assay Analytical Performance

Histoplasmosis is an important cause of mortality in people with advanced HIV, especially in countries with limited access to diagnostic assays. Histoplasmosis can be diagnosed using culture, histopathology, and antibody, antigen, and molecular assays. Several factors may affect the analytical performance of these laboratory assays, including sample type, clinical stage of the disease, and previous use of antifungal treatment, among others. Here we describe the results of a systematic literature review, followed by a meta-analysis of the analytical performances of the diagnostic laboratory assays employed. Our initial search identified 1631 references, of which 1559 references were excluded after title and abstract screening, leaving 72 references identified as studies relevant to the validation of histoplasmosis diagnostic assays. After evaluating the full text, 30 studies were selected for final review, including one paper not identified in the initial search. The meta-analysis for assay analytical performance shows the following results for the overall sensitivity (Sen) and specificity (Spe) of the various methods evaluated: Culture, Sen 77% (no data for specificity calculation); antibody detection assays, Sen 58%/Spe 100%; antigen detection assays, Sen 95%/Spe 97%; and DNA detection assays (molecular), Sen 95%/Spe 99%. Of the 30 studies reviewed, nearly half (n = 13) evaluated Histoplasma antigen assays, which were determined to be the most accurate methodology for diagnosis of progressive disseminated histoplasmosis in advanced HIV (inverse of the negative likelihood ratio was 13.2). Molecular assays appear promising for accurate diagnosis of histoplasmosis, but consensus on exact techniques is needed. Cultures showed variable sensitivity related to sample type and laboratory handling. Finally, antibody assays presented high specificity but low sensitivity. This poor sensitivity is most likely due the highly immunosuppressed state of this patient population. Diagnostic assays are crucial for accurate diagnosis of progressive disseminated histoplasmosis (PDH) with advanced HIV disease.

Histoplasmosis and Tuberculosis Co-Occurrence in People with Advanced HIV

Distinguishing between histoplasmosis, tuberculosis (TB), and co-occurrence of disease is a frequent dilemma for clinical staff treating people with advanced Human Immunodeficiency Virus (HIV) infection. This problem is most frequently observed in clinical settings in countries where both diseases are endemic. It is also a challenge outside these endemic countries in HIV clinics that take care of patients coming from countries with endemic histoplasmosis and TB. The gold standard for diagnosis of both of these diseases is based on conventional laboratory tests (culture, histopathology and special stains). These tests have several limitations, such as lack of laboratory infrastructure for handling isolates (biosafety level 3), shortage of laboratory staff who have appropriate training and experience, variable analytical performance of tests and long turn-around time. Recently, novel rapid assays for the diagnosis of histoplasmosis and TB became available. However, this technology is not yet widely used. Mortality in immunocompromised patients, such as people with advanced HIV, is directly linked with the ability to rapidly diagnose opportunistic diseases. The aim of this review is to synthesize the main aspects of epidemiology, clinical characteristics, diagnosis and treatment of histoplasmosis/TB co-occurrence in people with advanced HIV.

Emerging and reemerging fungal infections

Fungal infections throughout the world appear to be increasing. This may in part be due to the increase in the population of patients that are susceptible to otherwise rare fungal infections resulting from the use of immune modulating procedures such as hematopoietic stem cell transplants and drugs like tissue necrosis factor antagonists. Histoplasma capsulatum, an endemic fungus throughout North and South America, is reemerging among HIV+ patients in Central and South America and among patients taking tissue necrosis factor antagonists and other biologics in North America. Fusarium species, a relatively rare fungal infection, is reemerging worldwide in the immunocompromised populations, especially those who are neutropenic like hematopoietic stem cell transplant recipients. A new yeast species is currently emerging worldwide: Candida auris, unknown just a decade ago. It is causing large healthcare-associated outbreaks on four continents and is spreading throughout the world through patient travel. In this review the epidemiology, pathology, detection and treatment of these three emerging and reemerging fungi will be discussed.

Role of western blot assay for the diagnosis of histoplasmosis in AIDS patients from a National Institute of Infectious Diseases in Rio de Janeiro, Brazil

BACKGROUND

Histoplasmosis is a frequent fungal infection in HIV/AIDS patients, with high morbimortality rates when diagnosis and treatment are delayed. Antibody detection, which is faster than the gold standard culture test, hastens the laboratory investigation.

OBJECTIVES

To evaluate the role of WB for antibody detection in the diagnosis of histoplasmosis among HIV/AIDS patients.

PATIENTS AND METHODS

Fifty patients with proven or probable histoplasmosis were included. Clinical, epidemiological and laboratory data were described in the same population after a review of their medical records. WB was performed using deglycosylated histoplasmin.

RESULTS

About 82% of patients were adult males and the mean age was 39.3 years. CD4⁺ T lymphocyte count less than 150 cells/mm³ was observed in 62% patients. Antibodies against Histoplasma capsulatum M antigen were detected in 62% of patients, and against both M and H antigens in 28% of individuals. Sera from 10% of patients were nonreactive. Histoplasmosis was the first opportunistic infection in 38% of the cases. Disseminated and pulmonary histoplasmosis occurred in 84% and 16% of patients, respectively. The overall mortality was 16%.

CONCLUSION

WB could be useful for the histoplasmosis diagnosis in HIV/AIDS patients because of its easefulness and good sensitivity in a population where antibody production is hampered.

Histoplasma capsulatum antigen detection tests as an essential diagnostic tool for patients with advanced HIV disease in low and middle income countries: A systematic review of diagnostic accuracy studies

INTRODUCTION

Disseminated histoplasmosis, a disease that often resembles and is mistaken for tuberculosis, is a major cause of death in patients with advanced HIV disease. Histoplasma antigen detection tests are an important addition to the diagnostic arsenal for patients with advanced HIV disease and should be considered for inclusion on the World Health Organization Essential Diagnostics List.

OBJECTIVE

Our objective was to systematically review the literature to evaluate the diagnostic accuracy of Histoplasma antigen tests in the context of advanced HIV disease, with a focus on low- and middle-income countries.

METHODS

A systematic review of the published literature extracted data on comparator groups, type of histoplasmosis, HIV status, performance results, patient numbers, whether patients were consecutively enrolled or if the study used biobank samples. PubMed, Scopus, Lilacs and Scielo databases were searched for published articles between 1981 and 2018. There was no language restriction.

RESULTS

Of 1327 screened abstracts we included a total of 16 studies in humans for further analysis. Most studies included used a heterogeneousgroup of patients, often without HIV or mixing HIV and non HIV patients, with disseminated or non-disseminated forms of histoplasmosis. Six studies did not systematically use mycologically confirmed cases as a gold standard but compared antigen detection tests against another antigen detection test. Patient numbers were generally small (19-65) in individual studies and, in most (7/10), no confidence intervals were given. The post test probability of a positive or negative test were good suggesting that this non invasive diagnostic tool would be very useful for HIV care givers at the level of reference hospitals or hospitals with the infrastructure to perform ELISA tests. The first results evaluating point of care antigen detection tests using a lateral flow assay were promising with high sensitivity and specificity.

CONCLUSIONS

Antigen detection tests are promising tools to improve detection of and ultimately reduce the burden of histoplasmosis mortality in patients with advanced HIV disease.

Multicenter Validation of Commercial Antigenuria Reagents To Diagnose Progressive Disseminated Histoplasmosis in People Living with HIV/AIDS in Two Latin American Countries

Histoplasmosis is an important cause of mortality in patients with AIDS, especially in countries with limited access to antiretroviral therapies and diagnostic tests. However, many disseminated infections in Latin America go undiagnosed. A simple, rapid method to detect Histoplasma capsulatum infection in regions where histoplasmosis is endemic would dramatically decrease the time to diagnosis and treatment, reducing morbidity and mortality. The aim of this study was to validate a commercial monoclonal Histoplasma galactomannan (HGM) enzyme-linked immunosorbent assay (Immuno-Mycologics [IMMY], Norman, OK, USA) in two cohorts of people living with HIV/AIDS (PLHIV). We analyzed urine samples from 589 people (466 from Guatemala and 123 from Colombia), including 546 from PLHIV and 43 from non-PLHIV controls. Sixty-three of these people (35 from Guatemala and 28 from Colombia) had confirmed histoplasmosis by isolation of H. capsulatum Using the standard curve provided by the quantitative commercial test, the sensitivity was 98% (95% confidence interval [CI], 95 to 100%) and the specificity was 97% (95% CI, 96 to 99%) (cutoff = 0.5 ng/ml). Semiquantitative results, using a calibrator of 12.5 ng/ml of Histoplasma galactomannan to calculate an enzyme immunoassay index value (EIV) for the samples, showed a sensitivity of 95% (95% CI, 89 to 100%) and a specificity of 98% (95% CI, 96 to 99%) (cutoff ≥ 2.6 EIV). This relatively simple-to-perform commercial antigenuria test showed a high performance with reproducible results in both countries, suggesting that it can be used to detect progressive disseminated histoplasmosis in PLHIV in a wide range of clinical laboratories in countries where histoplasmosis is endemic.

Histoplasma Urinary Antigen Testing Obviates the Need for Coincident Serum Antigen Testing

OBJECTIVES

Serum and urine antigen (SAg, UAg) detection are common tests for Histoplasma capsulatum. UAg detection is more widely used and reportedly has a higher sensitivity. We investigated whether SAg detection contributes meaningfully to the initial evaluation of patients with suspected histoplasmosis.

METHODS

We reviewed 20,285 UAg and 1,426 SAg tests ordered from 1997 to 2016 and analyzed paired UAg and SAg tests completed on the same patient within 1 week. We determined the positivity rate for each test.

RESULTS

Of 601 paired specimens, 542 were concurrent negatives and 48 were concurrent positives (98% agreement). Medical records were available for eight of 11 pairs with discrepant results. UAg was falsely positive in six instances, truly positive once, and falsely negative once.

CONCLUSIONS

These findings support using a single antigen detection test, rather than both UAg and SAg, as an initial screen for suspected histoplasmosis. This aligns with the current practice of most physicians.

Discovery of a unique Mycobacterium tuberculosis protein through proteomic analysis of urine from patients with active tuberculosis

Identification of pathogen-specific biomarkers present in patients' serum or urine samples can be a useful diagnostic approach. In efforts to discover Mycobacterium tuberculosis (Mtb) biomarkers we identified by mass spectroscopy a unique 21-mer Mtb peptide sequence (VVLGLTVPGGVELLPGVALPR) present in the urines of TB patients from Zimbabwe. This peptide has 100% sequence homology with the protein TBCG_03312 from the C strain of Mtb (a clinical isolate identified in New York, NY, USA) and 95% sequence homology with Mtb oxidoreductase (MRGA423_21210) from the clinical isolate MTB423 (identified in Kerala, India). Alignment of the genes coding for these proteins show an insertion point mutation relative to Rv3368c of the reference H37Rv strain, which generated a unique C-terminus with no sequence homology with any other described protein. Phylogenetic analysis utilizing public sequence data shows that the insertion mutation is apparently a rare event. However, sera from TB patients from distinct geographical areas of the world (Peru, Vietnam, and South Africa) contain antibodies that recognize a purified recombinant C-terminus of the protein, thus suggesting a wider distribution of isolates that produce this protein.

Lower Respiratory Tract Infections

This review will focus on the infectious etiologies and more common noninfectious causes of lower respiratory tract syndromes among major immunosuppressed populations. The changing epidemiology of infections in the era of highly active antiretroviral therapy (HAART) in the case of HIV-positive patients and the impacts of both newer immune-suppressant therapies and anti-infective prophylaxis for other immunocompromised hosts will be discussed, with emphasis on diagnostic approaches and practice algorithms.

Disseminated histoplasmosis and AIDS: a prospective and multicentre study to evaluate the performance of different diagnostic tests

The burden of histoplasmosis has been poorly documented in most of the endemic areas for the disease, including Brazil. Also, modern non-culture-based diagnostic tests are often non-available in these regions. This was a prospective cohort study in HIV-infected patients with suspected disseminated disease evaluated with different diagnostic tests. Patients were enrolled in three referral medical centres in Porto Alegre, Brazil. Among 78 evaluated patients, disseminated histoplasmosis was confirmed in eight individuals (10.3%) by the means of classical (culture/histopathology) tests. Antigen detection in the urine was found to be more sensitive: IMMY^® ALPHA ELISA detected 13 positive cases (16.7%) and the in-house ELISA test developed by the Centers for Disease Prevention and Control (CDC) detected 14 (17.9%). IMMY^® and CDC tests provided concordant results in 96.2% of cases. This is the first study to compare the performance of the in-house CDC ELISA test with the IMMY^® commercial test for the diagnosis of histoplasmosis, and a high degree of concordance was observed. The study revealed that H. capsulatum is an important agent of disseminated disease in AIDS patients in Brazil, reinforcing the importance of making available modern diagnostic tests as well as safer antifungal agents for the treatment of histoplasmosis.