Platelia Aspergillus assay for diagnosis of disseminated histoplasmosis

Histoplasmosis in Solid Organ Transplantation

Histoplasma capsulatum, the etiological agent for histoplasmosis, is a dimorphic fungus that grows as a mold in the environment and as a yeast in human tissues. It has a broad global distribution with shifting epidemiology during recent decades. While in immunocompetent individuals infection is usually self-resolving, solid organ transplant recipients are at increased risk of symptomatic disease with dissemination to extrapulmonary tissue. Diagnosis of histoplasmosis relies on direct observation of the pathogen (histopathology, cytopathology, and culture) or detection of antigens, antibodies, or nucleic acids. All transplant recipients with histoplasmosis warrant therapy, though the agent of choice and duration of therapy depends on the severity of disease. In the present article, we describe the pathogenesis, epidemiology, clinical manifestations and management of histoplasmosis in solid organ transplant recipients.

Histoplasma antigen detection in unconfirmed pulmonary tuberculosis and cross-reactivity with Aspergillus antigen in patients and in food in Jakarta, Indonesia

PURPOSE

H. capsulatum is endemic in Indonesia, but the value of Histoplasma antigen detection has not been studied.

PATIENTS AND METHODS

Histoplasma galactomannan (GM) ELISA was applied to sera of patients with unproven pulmonary tuberculosis (TB) and patients with a positive Aspergillus GM. Both Histoplasma and Aspergillus GM tests were performed to determine any possible cross-reaction with certain foods.

RESULTS

Fourteen of 122 (11.5%) sera of patients with newly diagnosed clinical TB were positive for Histoplasma GM. The positivity rate in the serum of patients 5-6 and 12 months after TB diagnosis was 3.8% and 3.5%, respectively. Of 88 positive Aspergillus GM sera, 63 (71.6%) were also positive for Histoplasma GM. All tested foods were positive for Aspergillus GM, while 65% of foods were positive for Histoplasma GM.

CONCLUSION

Galactomannan is widespread in sera and food in Jakarta, possibly related to food consumption. Histoplasma and Aspergillus antigen detection for the diagnosis will require additional means of confirming the diagnosis; negative tests may be more helpful for ruling out invasive histoplasmosis and aspergillosis.

Evaluation of the EUROIMMUN Aspergillus antigen immunoenzyme assay in serum and bronchoalveolar lavage fluid samples

INTRODUCTION

The most widely used marker for the diagnosis of invasive aspergillosis (IA) is the detection of galactomannan by ELISA. This study describes the evaluation of the results obtained by Euroimmun Aspergillus antigen ELISA (EIA-GM-E) in serum samples and bronchoalveolar lavage fluid (BAL) from patients at risk of IA, and compares these results with those obtained by Bio-Rad Galactomannan EIA (EIA-GM-BR).

METHODS

Anonymous retrospective case-control comparative study in 64 serum samples and 28 BAL from 51 patients.

RESULTS

Overall agreement of the results of the two assays was observed in 72 of 92 samples (78.3%). The sensitivity of EIA-GM-BR and EIA-GM-E in serum samples was 88.9% and 43.2%, respectively, and 100% and 88.9% for BAL. The specificity of EIA-GM-BR and EIA-GM-E in serum samples was 91.9% for both assays, and 68.4% and 84.2% in BAL. There were no statistically significant differences in the results of both assays.

CONCLUSIONS

Both methods show good results for the discrimination of patients with IA when BAL is tested, or serum in case of EIA-GM-BR.

Comparison of Indirect Fungal Diagnostic Tests in Patients With Proven Histoplasmosis

BACKGROUND

Histoplasmosis is a common cause of invasive fungal infection in endemic regions and accurate diagnosis is difficult without direct tissue culture or pathology. Indirect fungal antigen testing for various fungal pathogens are typically performed to assist with diagnostic workup, though cross-reaction can lead to difficulty in interpreting results. We aimed to compare indirect fungal diagnostic tests and evaluate prevalence of positive antigen testing for non-Histoplasma fungal pathogens in patients with proven histoplasmosis.

METHODS

We performed a single-center retrospective review of adult patients with proven histoplasmosis diagnosed by fungal culture and/or cytology from January 2010 to March 2018. Patient demographics, clinical characteristics, and results of fungal antigen testing for Histoplasma, Blastomyces, Aspergillus, Cryptococcus, and (1→3)-β-D-glucan were evaluated. Two different urine Histoplasma antigen assays were used during the study period.

RESULTS

Fifty-seven of 182 (31.3%) patients reviewed had proven histoplasmosis and presented with acute pulmonary (n = 10), chronic pulmonary (n = 7), and disseminated (n = 40) disease. Forty-one (72%) of these patients were immunosuppressed. Urine Blastomyces antigen (93%) and serum (1→3)-β-D-glucan (88%) were commonly positive in patients with histoplasmosis, whereas Aspergillus antigen was detected in 50% of patients and Cryptococcus antigenemia was rare (5%). In patients with disseminated disease, the MiraVista urine Histoplasma antigen assay had higher sensitivity than the Viracor urine Histoplasma antigen assay (86% vs 50%, respectively; P = .019).

CONCLUSIONS

Noninvasive fungal antigen assays are helpful diagnostic tools; however, given their low specificity, clinicians must be aware of the various clinical presentations of invasive fungal infections and be aware of the limitations of these tests.

Performance of Two Commercial Assays for the Detection of Serum Aspergillus Galactomannan in Non-Neutropenic Patients

Besides the relevance of aspergillosis in neutropenic patients, this mycosis has gained significance among non-neutropenic patients in last years. The detection of Aspergillus galactomannan has been used for aspergillosis diagnosis and follow-up in neutropenic patients. This study evaluated the applicability of two commercial tests for galactomannan detection in non-neutropenic patients with different clinical forms of aspergillosis. Serum samples from patients with chronic pulmonary aspergillosis, aspergilloma, invasive aspergillosis, and COVID-19 associated pulmonary aspergillosis were evaluated using the IMMY sōna AGM lateral flow assay and the Bio-Rad Platelia sandwich ELISA. Serum specimens from patients with tuberculosis, histoplasmosis, paracoccidioidomycosis, and from healthy individuals were used as controls. The Bio-Rad Platelia sandwich ELISA presented greater sensitivity, whereas the IMMY sōna AGM lateral flow assay presented greater specificity. The accuracies of the tests were similar, as demonstrated by a receiver operator characteristic analysis. Moreover, the best cut-off values determined by this analysis were closer to that recommended by both manufacturers for neutropenic patients. The galactomannan indexes determined by different methodologies were strongly related, and a substantial agreement was observed between results. Both tests can be used in non-neutropenic patients with the cut-off values defined by the manufacturers. Histoplasma cross-reactions may occur in areas where histoplasmosis is endemic.

Acute Pulmonary Histoplasmosis Following COVID-19: Novel Laboratorial Methods Aiding Diagnosis

The acute form of histoplasmosis usually occurs after the exposition of more than one individual to a common environmental source harboring Histoplasma capsulatum. Here, we present two cases of acute pulmonary histoplasmosis seen within two weeks at a reference center for infectious diseases at Rio de Janeiro, Brazil. The patients did not present a common epidemiologic history for histoplasmosis, however both presented COVID-19 before the onset of histoplasmosis symptoms. Due to the difficulties in the diagnosis of acute histoplasmosis, novel laboratory methods such as Western Blot and PCR were included in the investigation of these cases. Both patients presented negative cultures for H. capsulatum and negative urinary galactomannan. However, they presented H and M bands in the Western blot as well as a positive H. capsulatum DNA detection in sputum. These results were available approximately 36 h after sample collection, fastening the beginning of treatment of one patient. Both patients progressed well with itraconazole treatment. These cases suggest that COVID-19 may facilitate the development of acute pulmonary histoplasmosis and, therefore, clinicians must be aware of this differential diagnosis in patients from endemic areas with fever and coughing after recovery from COVID-19.

Immunodiagnostic Assays for the Investigation of Fungal Outbreaks

Fungal pathogens can affect humans, animals, and plants, and they can be found in the environment or as part of the host microbiome. Fungal diseases present a broad clinical spectrum, ranging from superficial to invasive infections, and can cause outbreaks. During an outbreak investigation, the laboratory plays an essential role in verifying the diagnosis and helping to confirm the source of the outbreak. Immunodiagnostic assays are important tools and often relied upon for the diagnosis of fungal infections, since the gold standard assays of culture and histopathology are time-consuming and often require invasive procedures. Immunodiagnostic assays range from complement fixation and immunodiffusion to enzyme immunoassays and, most recently, to point-of-care lateral flow devices. In general, these assays provide results faster and offer good analytical performance. These characteristics make immunodiagnostic assays good laboratory tools for outbreak investigations. The aim of this review is to describe the principles, advantages, limitations, and availability of immunodiagnostics assays in outbreak investigations, based on the experience of a reference laboratory.

Amplification of blood smear DNA to confirm disseminated histoplasmosis

BACKGROUND

The prevalence of the Histoplasma capsulatum var. capsulatum (Hcc) histoplasmosis may be underestimated West Africa, both because the diagnosis is not mentioned in the early stages of the disease and due to limited biological resources available.

CASE REPORT

We report a case of disseminated histoplasmosis due to Hcc in a Senegalese HIV patient. The diagnosis was suspected following the demonstration of small encapsulated yeasts within neutrophils on a thin blood smear. It was further confirmed using a specific real-time PCR applied on a DNA specimen extracted from the thin blood smear.

CONCLUSION

To the best of our knowledge, this is the first case of Hcc infection diagnosed in Senegal. Blood smear may be a valuable screening tool in the case of bloodstream dissemination and can be used for further molecular approaches to confirm the diagnosis.

Progressive disseminated histoplasmosis: a systematic review on the performance of non-culture-based diagnostic tests

The diagnosis of progressive disseminated histoplasmosis is often a challenge to clinicians, especially due to the low sensitivity and long turnaround time of the classic diagnostic methods. In recent years, studies involving a variety of non-culture-based diagnostic tests have been published in the literature. We performed a systematic review by selecting studies evaluating non-culture-based diagnostic methods for progressive disseminated histoplasmosis. We searched for articles evaluating detection of antibody, antigens, as well as DNA-based diagnostic methods. A comprehensive PUBMED, Web of Science, and Cochrane Library search was performed between the years 1956 and 2016. Case reports, review articles, non-human models and series involving less than 10 patients were excluded. We found 278 articles and after initial review 18 articles were included: (12) involved antigen detection methods, (4) molecular methods, and (2) antibody detection methods. Here we demonstrate that the pursuit of new technologies is ultimately required for the early and accurate diagnosis of disseminated histoplasmosis. In particular, urinary antigen detection was the most accurate tool when compared with other diagnostic techniques.

Disseminated histoplasmosis partially mimicking a dermatomyositis in a patient with rheumatoid arthritis

Histoplasma capsulatum var. capsulatum is a dimorphic fungus endemic to America and subtropical regions. Several cases of this opportunist mycosis have been reported in immunocompromised patients. We report the case of a patient treated with methotrexate and corticosteroid therapy for rheumatoid arthritis and who presented with disseminated histoplasmosis that partially mimicked a dermatomyositis.

Late occurrence of Histoplasma duboisii cutaneous and pulmonary infection 18 years after exposure

We report an imported case of Histoplasma capsulatum var. duboisii (H. duboisii) infection in a white French woman revealed by cutaneous lesions of the scalp, 18 years after her last stay in West and Central Africa. Asymptomatic bilateral pulmonary infiltrates were discovered on thoracic computed tomography. Skin biopsy allowed the positive diagnosis showing the typical yeasts; culture of biopsy specimens was positive for H. capsulatum. In the absence of criteria of severity, the patient was treated for one year with oral itraconazole 400mg/day. The outcome was favourable, skin and pulmonary lesions resolved slowly. The follow up is 5 years without relapse after the end of treatment. This case illustrates the possibility of late occurrence of H. duboisii infection, many years after exposure and the major importance of asking any patient for travelling or residency in tropical countries.

A complementary tool for management of disseminated Histoplasma capsulatum var. capsulatum infections in AIDS patients

In South America, disseminated histoplasmosis due to Histoplasma capsulatum var. capsulatum (H. capsulatum), is a severe and frequent opportunistic infection in AIDS patients. In areas outside the USA where specific-Histoplasma antigen detection is not available, the diagnosis is difficult. With the galactomannan antigen (GM) detection, a test commonly used for invasive aspergillosis diagnosis, there is a cross-reactivity with H. capsulatum that can be helpful for the diagnosis of histoplasmosis. The aim of this study was to evaluate the GM detection for the diagnosis of disseminated histoplasmosis in AIDS patients. The performance of the GM detection was evaluated with serum collected in French Guiana where H. capsulatum is highly endemic. Sera from AIDS patients with disseminated histoplasmosis occurring from 2002 to 2009 and from control HIV-positive patients without histoplasmosis were tested with the GM detection and Histoplasma-specific antibody detection (IEP). In 39 AIDS patients with proven disseminated histoplasmosis, the sensitivity of the Histoplasma IEP was only 35.9% and was linked to the TCD4+ lymphocyte level. For the GM detection, the sensitivity (Se) was 76.9% and specificity (Sp) was 100% with the recommended threshold for aspergillosis diagnosis (0.5). The test was more efficient with a threshold of 0.4 (Se: 0.82 [95% CI: 0.66-0.92], Sp: 1.00 [95% CI: 0.86-1.00], LR+: >10, LR-: 0.18). This study confirms that the GM detection can be a surrogate marker for the diagnosis of disseminated histoplasmosis in AIDS patients in endemic areas where Histoplasma EIA is not available.

Histoplasmosis in HIV-Infected Patients: A Review of New Developments and Remaining Gaps

Histoplasma capsulatum is responsible for histoplasmosis, a fungal disease with worldwide distribution that can affect both immunocompromised and imunocompetent individuals. During the highly active antiretroviral therapy (HAART) era, morbidity and mortality due to histoplasmosis remained a public heatlh problem in low-income and high-income countries. The true burden of HIV-associated histoplasmosis is either not fully known or neglected since it is not a notifiable disease. Progress has been made in DNA patterns of strains and understanding of pathogenesis, and hopefully these will help identify new therapeutic targets. Unfortunately, histoplasmosis is still widely mistaken for multidrug-resistant tuberculosis, leading to numerous avoidable deaths, even if they are easily distinguishable. The new diagnostic tools and therapeutics developments have still not been made available in most endemic regions. Still, recent developments are promising because of their good clinical characteristics and also because they will be commercially available and affordable. This review of published data and gaps may help define and guide future research.

[Aspergillus galactomannan assay for the management of histoplasmosis due to Histoplasma capsulatum var. duboisii in HIV-infected patients: education from a clinical case]

The diagnosis of histoplasmosis due to Histoplasma capsulatum var capsulatum is based on a direct examination identifying encapsulated yeast with narrow-based budding. Galactomannan antigenemia facilitates diagnosis, as well as the monitoring of patients receiving treatment. The case of a HIV-positive patient from Congo-Brazzaville with a disseminated form of African histoplasmosis highlighted the positive galactomannan antigen in this disease due to Histoplasma capsulatum var duboisii. Galactomannan antigenemia remained high with a very slow decrease during antifungal therapy and slow regression of clinical lesions. African histoplasmosis is a rare disease that is difficult to diagnose and rarely described in immunocompromised patients, in whom differential diagnosis can be common. This observation underlines the importance of the galactomannan antigen assay in patients who have travelled to endemic areas. As in the case of Histoplasma capsulatum var capsulatum, the positivity of the Aspergillus galactomannan antigen is very useful in the diagnosis and monitoring of African histoplasmosis.

Cross-reactivity of Aspergillus galactomannan in an HIV-infected patient with histoplasmosis

Non-invasive assays are increasingly being used in patients with suspected fungal infections. Limitations to these tests include limited sensitivity, specificity, and cross reactivity with other fungal pathogens. Herein we report a case of disseminated histoplasmosis producing a false positive serum and bronchoalveolar lavage (BAL) Aspergillus galactomannan assays. This test may have a role in the evaluation of patients with suspected histoplasmosis in settings where Histoplasma antigen testing is not widely available.

Seven imported histoplasmosis cases due to Histoplasma capsulatum var. capsulatum: From few weeks to more than three decades asymptomatic period

Histoplasma capsulatum is a nonendemic fungus in Europe. Epidemiological, clinical biological features and follow-up of seven imported cases in France were reported. These cases underlined the difficulties of such diagnosis in nonendemic areas due to greatly variable asymptomatic period, and lack of specific clinical signs. Thus, anamnesis should be carefully analysed; mucocutaneous signs and immunosuppression should be systematically investigated. Biological diagnosis requires multiple sites sampling and long-term conservation of culture medium.

[Contribution of molecular biology and Aspergillus galactomannan antigen assay for the diagnosis of histoplasmosis]

We report a case of a pulmonary histoplasmosis in an HIV-positive patient usually living in Cambodia, with a positive Aspergillus galactomannan antigenemia resulting from a cross-reaction, that decreased after antifungal therapy. We discuss the potential interest of the detection of fungal DNA by PCR and Aspergillus galactomannan antigenemia for the diagnosis of histoplasmosis, especially in countries where Histoplasma capsulatum antigen testing is not available.