Histoplasmosis: presentaciones clínicas y pruebas de laboratorio en un centro brasileño

Histoplasmosis in Non-HIV Infected Patients: Another Neglected Infection in French Guiana

(1) Background: Only a few studies on histoplasmosis in immunocompetent patients have been reported in French Guiana. Therefore, we conducted a detailed clinical description of hospitalized patients suffering with histoplasmosis among non-HIV patients. (2) Methods: This is a single-center, retrospective study conducted at Cayenne Hospital Center between 2008 and 2022. (3) Results: Our cohort was composed of 31 (91%) adults (>18 years of age) and 3 (9%) children, with a sex ratio, M:F, of 1:2. The median age was higher among the women than among the men (70 versus 54 years). The collection of respiratory samples constituted the majority of the performed examinations (38%). Fever (>37 °C) was found in 56% of patients. Surprisingly, the histoplasmosis was disseminated in 82% of patients with an overall case fatality rate of 14.7%. However, immunosuppressive conditions were found in 52% (16/31) of the adult patients, including lymphoid hemopathies, diabetes and immunosuppressive drugs. Conclusions: This disease, though rare and usually considered a mostly benign disease in non-HIV patients, presented a relatively high mortality rate in our cohort. Thus, histoplasmosis should be suspected, screened and investigated as a first line of defense in highly endemic areas, even in immunocompetent and non-HIV patients, especially those with fever or chronic respiratory symptoms.

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.

Genomic Diversity Analysis Reveals a Strong Population Structure in Histoplasma capsulatum LAmA (Histoplasma suramericanum)

Histoplasmosis is a severe mycotic disease affecting thousands of immunocompetent and immunocompromised individuals with high incidence in Latin America, where the disease agents are Histoplasma capsulatum and Histoplasma suramericanum. In this work, we used whole-genome sequencing to infer the species diversity and the population structure of H. suramericanum in South America. We find evidence for strong population structure and little admixture within the species. Genome-level phylogenetic trees indicate the existence of at least three different discrete populations. We recovered the existence of a previously identified population, LAmB, and confirm that it is highly differentiated along the whole genome. We also find that H. suramericanum is composed of two populations, one in Northern South America, and another in the southern portion of the continent. Moreover, one of the lineages from the southern population is endemic to Rio de Janeiro and there was no association with clinical data and species isolated from patients with histoplasmosis. Our results point out the need to characterize the symptomatology of histoplasmosis caused by different species and lineages of Histoplasma spp.

Cutaneous Histoplasmosis in HIV Seronegative Patients: A Clinicopathological Analysis

BACKGROUND

Diagnosis of extrapulmonary histoplasmosis in HIV seronegative and immunocompetent patients is often challenging, so a high index of suspicion is required. Cutaneous manifestation of infection shows a wide spectrum of lesions including erythematous plaques; maculopapules; crusted, verrucous, or desquamative papules and nodules; abscesses; and mucocutaneous ulcers among others. Due to the variations in its clinical presentation, histopathology plays a very important role in the detection of spores and the confirmation of diagnosis.

OBJECTIVES

The aim of our study was to analyze clinicopathological characteristics of cutaneous manifestations of biopsy-proven histoplasmosis in HIV seronegative individuals. We also examined the utility of Fite stain for the diagnosis of Histoplasma capsulatum on tissue biopsy sections.

METHODS

This was a retrospective, observational study on 7 patients who were HIV seronegative and clinically manifested with isolated cutaneous lesions or disseminated disease. Skin biopsy from the lesions was performed on all 7 patients. In addition to H&E staining and special stains for detecting fungus, Fite staining was performed on all of the cases to study its utility in detecting H. capsulatum spores.

RESULTS

The skin lesions were widely disseminated in all patients and the most common cutaneous lesions were papules, present in all 7 patients. On review of the H&E-stained slides, the most common pattern was histiocytic lobular panniculitis-like infiltrate observed in 4 cases. Fite stain highlighted the yeast as magenta-colored spores on a blue background in all cases, except for 1 with a granulomatous pattern.

CONCLUSION

A primary cutaneous manifestation of H. capsulatum infection in non-HIV-infected individuals is extremely rare. Fite stain could aid in differentiating the spores of H. capsulatum from those of other fungi, Cryptococcus and Candida in particular.

Diagnosis of Breakthrough Fungal Infections in the Clinical Mycology Laboratory: An ECMM Consensus Statement

Breakthrough invasive fungal infections (bIFI) cause significant morbidity and mortality. Their diagnosis can be challenging due to reduced sensitivity to conventional culture techniques, serologic tests, and PCR-based assays in patients undergoing antifungal therapy, and their diagnosis can be delayed contributing to poor patient outcomes. In this review, we provide consensus recommendations on behalf of the European Confederation for Medical Mycology (ECMM) for the diagnosis of bIFI caused by invasive yeasts, molds, and endemic mycoses, to guide diagnostic efforts in patients receiving antifungals and support the design of future clinical trials in the field of clinical mycology. The cornerstone of lab-based diagnosis of breakthrough infections for yeast and endemic mycoses remain conventional culture, to accurately identify the causative pathogen and allow for antifungal susceptibility testing. The impact of non-culture-based methods are not well-studied for the definite diagnosis of breakthrough invasive yeast infections. Non-culture-based methods have an important role for the diagnosis of breakthrough invasive mold infections, in particular invasive aspergillosis, and a combination of testing involving conventional culture, antigen-based assays, and PCR-based assays should be considered. Multiple diagnostic modalities, including histopathology, culture, antibody, and/or antigen tests and occasionally PCR-based assays may be required to diagnose breakthrough endemic mycoses. A need exists for diagnostic tests that are effective, simple, cheap, and rapid to enable the diagnosis of bIFI in patients taking antifungals.

Histoplasmosis Outbreaks in Brazil: Lessons to Learn About Preventing Exposure

Histoplasmosis is considered the most common invasive opportunistic fungal disease in the Americas, with outbreaks and micro-epidemics reported for over 80 years. In Brazil, this disease has been described since 1946, reaching a remarkable incidence in the population, especially during the HIV-AIDS pandemic. In this study, published and unpublished outbreaks and micro-epidemics of histoplasmosis in Brazil were revisited by accessing different database sources and evaluating epidemiological and clinical features. We have found reports spanning 1946-2017, across 10 Brazilian states and with involvement of 370 humans and 2 dogs, and 13 disseminated cases and 3 deaths were reported. Rio de Janeiro had the largest number of outbreaks (n = 20/40; 50%) reported in this study. The majority of outbreaks and micro-epidemics was reported in caves (n = 21/40; 52.5%), followed by reports in abandoned/deactivated sites (n = 6/40; 15%), mines (n = 5/40; 12.5%), chicken coops (n = 4/40; 10%). Histoplasmosis is a serious health issue in Brazil considering the attractive and growing market of ecotourism throughout more than 7000 caves, and all levels of poultry farming activity are important to raise awareness about how dangerous this neglected disease can be and establish ways to decrease exposure to contaminated environmental sources through adequate preventive measures.

Imported endemic mycoses in Spain: Evolution of hospitalized cases, clinical characteristics and correlation with migratory movements, 1997-2014

Endemic mycoses are systemic fungal infections. Histoplasmosis is endemic in all temperate areas of the world; coccidioidomycosis and paracoccidioidomycosis are only present in the American continent. These pathogens are not present in Spain, but in the last years there has been an increase of reported cases due to migration and temporary movements. We obtained from the Spanish hospitals records clinical and demographic data of all hospitalized cases between 1997 and 2014. There were 286 cases of histoplasmosis, 94 of Coccidioidomycosis and 25 of paracoccidioidomycosis. Overall, histoplasmosis was strongly related to HIV infection, as well as with greater morbidity and mortality. For the other mycoses, we did not find any immunosuppressive condition in most of the cases. Although we were not able to obtain data about clinical presentation of all the cases, the most frequently found was pulmonary involvement. We also found a temporal correlation between the Spanish population born in endemic countries and the number of hospitalized cases along this period. This study reflects the importance of imported diseases in non-endemic countries due to migratory movements.

Fast protocol for the production of Histoplasma capsulatum antigens for antibody detection in the immunodiagnosis of histoplasmosis

BACKGROUND

Current methods for the production of Histoplasma capsulatum antigens are problematic in terms of standardization, specificity, stability, repeatability and reproducibility.

AIMS

In this study, we sought to optimize the methodology for producing H. capsulatum antigens, and to evaluate its applicability.

METHODS

Antigenic preparations obtained from 12 H. capsulatum isolates were evaluated by double immunodiffusion and immunoblotting assays against homologous and heterologous sera.

RESULTS

The evaluated and optimized protocol allowed a more stable production, as well as repeatable, reproducible, with shorter culture time and less costly. By double immunodiffusion and immunoblotting assays, the best pattern of reactivity was observed for antigens obtained with 33 days of culture from the isolates 200 and 406 against the M antigen and for the isolate 200 with 15 days against H antigen. The SDS-PAGE presented antigenic components of molecular masses between 17 and 119kDa. The immunoblotting sensitivity was 95.5% and 100% with histoplasmosis sera from ill patients and sera from H. capsulatum infected but otherwise healthy patients, respectively, to the antigen derived from isolates 200 and 406.

CONCLUSIONS

We suggest the employment of the antigen from isolate 200, with 15 or 30 days of culture, in the double immunodiffusion and immunoblotting assays due to its good ability to discriminate both sera from patients with histoplasmosis illness and histoplasmosis infection, in addition to its high specificity against heterologous sera.

The Changing Epidemiology of Invasive Fungal Infections

Invasive fungal infections (IFI) are an emerging problem worldwide with invasive candidiasis and candidemia responsible for the majority of cases. This is predominantly driven by the widespread adoption of aggressive immunosuppressive therapy among certain patient populations (e.g., chemotherapy, transplants) and the increasing use of invasive devices such as central venous catheters (CVCs). The use of new immune modifying drugs has also opened up an entirely new spectrum of patients at risk of IFIs. While the epidemiology of candida infections has changed in the last decade, with a gradual shift from C. albicans to non-albicans candida (NAC) strains which may be less susceptible to azoles, these changes vary between hospitals and regions depending on the type of population risk factors and antifungal use. In certain parts of the world, the incidence of IFI is strongly linked to the prevalence of other disease conditions and the ecological niche for the organism; for instance cryptococcal and pneumocystis infections are particularly common in areas with a high prevalence of HIV disease. Poorly controlled diabetes is a major risk factor for invasive mould infections. Environmental factors and trauma also play a unique role in the epidemiology of mould infections, with well-described hospital outbreaks linked to the use of contaminated instruments and devices. Blastomycosis is associated with occupational exposure (e.g., forest rangers) and recreational activities (e.g., camping and fishing).The true burden of IFI is probably an underestimate because of the absence of reliable diagnostics and lack of universal application. For example, the sensitivity of most blood culture systems for detecting candida is typically 50 %. The advent of new technology including molecular techniques such as 18S ribosomal RNA PCR and genome sequencing is leading to an improved understanding of the epidemiology of the less common mould and dimorphic fungal infections. Molecular techniques are also providing a platform for improved diagnosis and management of IFI.Many factors affect mortality in IFI, not least the underlying medical condition, choice of therapy, and the ability to achieve early source control. For instance, mortality due to pneumocystis pneumonia in HIV-seronegative individuals is now higher than in seropositive patients. Of significant concern is the progressive increase in resistance to azoles and echinocandins among candida isolates, which appears to worsen the already significant mortality associated with invasive candidiasis. Mortality with mould infections approaches 50 % in most studies and varies depending on the site, underlying disease and the use of antifungal agents such as echinocandins and voriconazole. Nevertheless, mortality for most IFIs has generally fallen with advances in medical technology, improved care of CVCs, improved diagnostics, and more effective preemptive therapy and prophylaxis.

Primary Cutaneous Histoplasmosis Masquerading as Lepromatous Leprosy

Histoplasmosis is a genus of dimorphic fungi having various varieties of which the commonest one causing infection is Histoplasma capsulatum known to cause histoplasmosis. It has a varied disease spectrum ranging from an acute infection to chronic disease especially in lungs, disseminated disease and cutaneous disorder. Histoplasma capsulatum usually causes subclinical infection and serious infections only manifest in immunocompromised patients. Frank cases of infection are seen in pulmonary histoplasmosis. The spores of these organisms are seen to be strongly associated with droppings of birds and bats. A combination of these droppings and some soil types provide for an excellent environment for the proliferation of spores. Pulmonary histoplasmosis and disseminated disease are very common in AIDS patients and are a great cause of morbidity and mortality in these patients. Primary cutaneous histoplasmosis is very rare and occurs due to penetrating injuries. Once diagnosis is made, the lesions respond very well to oral itraconazole, fluconazole or amphotericicn B. We report a rare case of Cutaneous Histoplasmosis (CHP) in a 70-year-old male with complaints of multiple nodules all over his body in a HIV seronegative and otherwise immunocompetent patient.

Prevalence and lethality among patients with histoplasmosis and AIDS in the Midwest Region of Brazil

Histoplasmosis is a systemic mycosis that is considered an important public health problem. In this work, we performed a descriptive, observational, cross-sectional and retrospective study with a secondary data analysis of medical records from 2000 to 2012 at a tertiary hospital. The study sample consisted of 275 patients with laboratory-confirmed Disseminated Histoplasmosis (DH)/AIDS. The results showed that the prevalence of DH associated with AIDS was 4.4%. The majority of patients were young adult men with fever in 84.2%, cough in 63.4%, weight loss in 63.1%, diarrhoea in 44.8% and skin manifestations in 27.6% of patients. In the overall cohort, the CD4 counts were low, but not significantly different in survivors and non-survivors. Higher levels of urea and lower levels of haemoglobin and platelets were observed in non-survivor patients (<.05). The global lethality was 71.3% (196/275). The results with high prevalence and lethality highlight the need to adopt measures to facilitate early diagnosis, proper treatment and improved prognosis.

DISSEMINATED FUNGAL INFECTION WITH ADRENAL INVOLVEMENT: REPORT OF TWO HIV NEGATIVE BRAZILIAN PATIENTS

Paracoccidioidomycosis and histoplasmosis are systemic fungal infections endemic in Brazil. Disseminated clinical forms are uncommon in immunocompetent individuals. We describe two HIV-negative patients with disseminated fungal infections, paracoccidioidomycosis and histoplasmosis, who were diagnosed by biopsies of suprarenal lesions. Both were treated for a prolonged period with oral antifungal agents, and both showed favorable outcomes.

Validation of western blot for Histoplasma capsulatum antibody detection assay

BACKGROUND

Histoplasmosis is worldwide systemic mycoses caused by the dimorphic fungus Histoplasma capsulatum. The isolation and identification of H. capsulatum in culture is the reference test for histoplasmosis diagnosis confirmation. However, in the absence of it, serology has been used as a presumptive diagnosis through antibody and antigen detection. The purpose of the present study was to validate an immunoassay method (western blot) for antibodies detection in the diagnosis of histoplasmosis.

METHODS

To validate the western blot (WB) a study was conducted using 118 serum samples from patients with histoplasmosis and 118 serum controls collected from January 2000 to December 2013 in residents of the Rio de Janeiro State, Brazil. Diagnostic validation parameters were calculated based on the categorization of results obtained in a 2 × 2 table and subjected to statistical analysis. In addition, the viability of deglycosylated histoplasmin antigen (ptHMIN) onto nitrocellulose membranes previously sensitized was evaluated during the same period.

RESULTS

The WB test showed sensitivity of 94.9 %, specificity of 94.1 %, positive predictive value of 94.1 %, negative predictive value of 94.9 %, accuracy of 94.5 %, and almost perfect precision. Besides, the strips have proved to be viable for using at least 5 years after ptHMIN antigen sensitization.

CONCLUSION

Western blot test using ptHMIN provides sensitive, specific, and faster results. Therefore, could be considered a useful tool in the diagnosis of histoplasmosis being used by public health system, even in situations where laboratory facilities are relatively limited.

Immunological assays employed for the elucidation of an histoplasmosis outbreak in São Paulo, SP

Several reports showed outbreaks of histoplasmosis acquired while bat-inhabited caves were visited by tourists, miners or researchers. We evaluated the performance of double immunodifusion (DI) and immunoblotting (IB) assays, employed for the histoplasmosis outbreak elucidation occurred in Vale do Paraíba, São Paulo. The existence of epidemiologic link, four patients with clinical signs suggestive of histoplasmosis and mycological confirmation has made that all 35 individuals involved to the cave visit were subjected to serological evaluation. By DI, we observed reactivity against H. capsulatum antigen in a single serum examined nearly 20 days after exposure to fungal propagules. On the other hand, IB showed reactivity against H and M fractions in 50% of samples evaluated. The analysis of the second sample batch, collected two months after the exposure showed that 96.7% were reactive by DI with antibodies titers ranging from 1 to 16 and 100% of reactivity against H and M fractions, by IB, suggesting an acute infection. The analysis of the overall agreement between the methods showed to be reasonable (κ = 0.37). This study confirms the importance and efficacy of more sensitive methodologies, such as IB assay, to early elucidation of disease, especially in cases of patients without mycological information.

Diagnostic Methods for Histoplasmosis: Focus on Endemic Countries with Variable Infrastructure Levels

Diagnosis of histoplasmosis remains challenging in resource-limited regions where HIV/AIDS is epidemic and histoplasmosis is endemic. Early and rapid detection of histoplasmosis is essential to preventing morbidity and mortality, yet few diagnostic options are available in low-resource areas of the world. The aim of this review is to provide an overview of the current status of the diagnosis of histoplasmosis, including an update on recent developments and utilization of new technologies. We discuss the specific diagnostic challenges faced in endemic regions, emphasizing the need for greater availability and standardization of rapid diagnostics for this endemic and neglected disease. While significant progress has been made in the development of new methods, clinical utility must be established by means of formal and extensive clinical studies.

A gingival manifestation of histoplasmosis leading diagnosis

Histoplasmosis is a world-wide distributed deep mycosis caused by Histoplasma capsulatum which has been endemic in many countries. We present a case involving an immunocompetent man evidencing the necessity of a multidisciplinary approach and rational requisition of exams. The disease has started as a pulmonary disease mimicking tuberculosis, although the exams have been negative. Immunodiffusion test indicate histoplasmosis, not confirmed by culture of sputum. After days the patient was forwarded by a private doctor for evaluation of oral lesions at our Department of Stomatology. An incisional biopsy revealed a nonspecific granulomatous inflammation and the Grocott-Gomori methenamine silver stain identified scarce oval structures that could represent fungal yeast. Sampling oral lesions with swab, it was observed the typical growth of H. capsulatum on culture. This case highlights the importance of doctor's integration diagnosing histoplasmosis, while a wide spectrum of clinical manifestations should be expected. Oral lesions may be the critical manifestation leading diagnosis.

Identification of fungal diseases at necropsy

The purpose of the Death Verification Service is to elucidate the causes of deaths that occur without medical assistance and of ill-defined deaths. In recent decades, the epidemiological reality of fungal infections has changed due to the rise in opportunistic infections chiefly in immunocompromised patients. A study of fungal diseases in autopsies performed in the Death Verification Service of the Medicine School in São José do Rio Preto between January 2000 and December 2009 was made. Sixty-seven cases of fungal disease, most involving men (70%), were found in 4824 autopsies. Cryptococcosis was the most prevalent (45%), followed by paracoccidioidomycosis, candidiasis, histoplasmosis, aspergillosis and mucormycosis. Associations between AIDS (n=14) and fungal diseases were identified for cryptococcosis (36%), candidiasis (28.5%) and histoplasmosis (28.5%). Pneumonia, AIDS and fungal diseases were evident in 26% of the cases, with the most prevalent etiologies being Cryptococcus neoformans (55.5%) and Histoplasma capsulatum (22%). Pneumonia alone occurred in 43% of cases, with cryptococcosis (53%) and paracoccidioidomycosis (33%) being the main infectious agents. Diabetes mellitus was associated with candidiasis in two cases and aspergillosis in one. One case of renal transplantation linked to paracoccidioidomycosis and one case of bone marrow aplasia with mucormycosis were reported. Despite the reduction in the number of autopsies over recent decades, these findings suggest that this procedure is useful to provide additional data on the etiology, underlying disease and specific risk factors, essential for quality control and to improve treatment protocols.

Usefulness of oral cytopathology in the diagnosis of infectious diseases

In recent years, the incidence of oral opportunistic infections has increased, partly due to the widespread implementation of organ and bone marrow transplantation and the increase in the prevalence of human immunodeficiency virus (HIV) infection. Cytology can be used as a rapid, inexpensive and simple routine procedure in diagnosing infectious diseases of the mouth. Moreover, ancillary methods can be applied to cytological samples, increasing the specificity and sensitivity for the diagnosis of infectious diseases. This review describes the cytopathological features of the main viral, fungal, bacterial and parasitic infections of the mouth. Cytological techniques of specimen collection, identification of infectious agents by cytomorphological approaches and ancillary methods, and diagnostic pitfalls will be discussed.

Evaluation of an enzyme-linked immunosorbent assay using purified, deglycosylated histoplasmin for different clinical manifestations of histoplasmosis

Diagnosis of invasive fungal diseases remains problematic, especially in undeveloped countries. We have developed an enzyme-linked immunosorbent assay (ELISA) for the detection of antibodies to Histoplasma capsulatum using metaperiodate treated purified histoplasmin (ptHMIN). Our ELISA was validated comparing sera from patients with histoplasmosis, related mycoses, and healthy individuals. The overall test specificity was 96%, with sensitivities of 100% (8/8) in acute disease, 90% (9/10) in chronic disease, 89% (8/9) in disseminated infection in individuals without HIV infection, 86% (12/14) in disseminated disease in the setting of HIV infection and 100% (3/3) in mediastinal histoplasmosis. These parameters are superior to the use of untreated histoplasmin in diagnostic ELISAs. The high specificities, sensitivities, and simplicity of our ELISA support further development of a deglycosylated HMIN ELISA for clinical use and for monitoring the humoral immune response during therapy in patients with chronic and disseminated histoplasmosis.

Soluble components of Histoplasma capsulatum var. capsulatum have hemagglutinin activity and induce syngeneic hemophagocytosis in vitro

Histoplasma capsulatum var. capsulatum is a thermally dimorphic fungus that causes histoplasmosis. Fungal hemagglutination activity and cases of reactive hemophagocytic syndrome (RHS) have been reported in the disseminated form of disease. In the present study, soluble components of H. capsulatum var. capsulatum have been investigated for hemagglutinin activity and the capacity to induce hemophagocytosis in the mouse system. To analyze hemagglutinating activity, mouse red blood cells (RBC) (1% v/v in PBS) were incubated (37 degrees C, 1 h) with cell-free antigen (CFAg) from H. capsulatum var. capsulatum (isolate IMT/HC128) (RBC-CFAg) or previously heated CFAg (56 degrees C, 30 min) (RBC-hCFAg) or as control with PBS (RBC-PBS). Hemophagocytosis was analyzed by incubating BALB/c mouse peritoneal phagocytic cells (5 x 10(6) cells) with syngeneic RBC, sensitized or not with CFAg. In addition, mouse polyclonal antibodies were raised against syngeneic RBC-CFAg (anti-RBC-CFAg) and used to analyze CFAg chromatographic fractions (Sephadex G75/120) by immunoenzymatic assay (ELISA). Hemagglutinin activity was observed with RBC-CFAg, but not with RBC-hCFAg or RBC. Also, hemophagocytosis was observed with RBC-CFAg, but not with RBC. The anti-RBC-CFAg antibodies reacted with CFAg fractions corresponding to a molecular mass (MM) higher than 150 kDa. In conclusion, the yeast form of H. capsulatum var. capsulatum releases thermolabile soluble components with hemagglutinin activity and it has been demonstrated for the first time that soluble components of the same fungus induce syngeneic hemophagocytosis in the in vitro mouse system. Also, indirect analysis with antibodies suggests that high-MM components (>150 kDa) are responsible for the interaction with RBC.

Development and evaluation of an enzyme-linked immunosorbent assay to detect Histoplasma capsulatum antigenuria in immunocompromised patients

Histoplasma capsulatum infection causes significant morbidity and mortality in human immunodeficiency virus-infected individuals, particularly those in countries with limited access to rapid diagnostics or antiretroviral therapies. The fungus easily disseminates in persons with AIDS, resulting in progressive disseminated histoplasmosis (PDH), which can progress rapidly to death if undiagnosed. The availability of a simple, rapid method to detect H. capsulatum infection in less developed countries where the infection is endemic would dramatically decrease the time to diagnosis and treatment of PDH. We have developed an antigen-capture enzyme-linked immunosorbent assay (ELISA) to detect PDH antigenuria in infected patients. The assay uses polyclonal antibodies against H. capsulatum as both capture and detection reagents, and a standard reference curve is included to quantify antigenuria and ensure reproducibility. We evaluated this assay using specimens collected from patients with AIDS and culture-proven histoplasmosis in a Guatemalan clinic (n = 48), from healthy persons (n = 83), and from patients with other, nonhistoplasmosis diseases (n = 114). The ELISA demonstrated a sensitivity of 81% and a specificity of 95% in detecting H. capsulatum antigen in urine. This assay relies on simple technology that can be performed in institutions with limited resources. Use of this test will facilitate rapid diagnosis of PDH in countries where mortality is high, expediting treatment and likely reducing PDH-related mortality.

Histoplasmosis: a study of 158 cases in Venezuela, 2000-2005

Histoplasmosis, a granulomatous disease caused by Histoplasma capsulatum, is endemic in Venezuela. We conducted the current study to appraise retrospectively the demographic data, clinical features, diagnostic methods, and treatment of patients with histoplasmosis from January 2000 to December 2005. We reviewed the medical records of outpatient cases with a diagnosis of histoplasmosis and considered clinical samples processed at our laboratory. We collected demographic, epidemiologic, and clinical data from each case as available, including results of any mycologic examinations performed. Treatment and outcome data were available for some patients. We assessed 158 cases of histoplasmosis: 103 (65.2%) patients came from the Caracas metropolitan area; 53 were associated with acquired immunodeficiency syndrome (AIDS), 14 with tuberculosis, and 8 with paracoccidioidomycosis. Six pediatric patients were malnourished. Epidemiologic data suggested histoplasmosis in most cases. Patients received treatment with itraconazole and/or amphotericin B. Our results may reflect changes in the epidemiology occurring in Venezuela, perhaps due to environmental changes and the presence of AIDS. Several mycologic exams are necessary to ensure a proper diagnosis. More reliable data and statistics on this infection are necessary to monitor outbreaks closely and to establish if there is an epidemic pattern.

Histoplasmosis in Europe: report on an epidemiological survey from the European Confederation of Medical Mycology Working Group

The purpose of this survey was to systematically collect data on individuals with histoplasmosis in Europe over a 5-year period (from January 1995 to December 1999). This included information on where and how the infection was acquired, the patient's risk factors, the causative organism, how the infection was diagnosed and what therapy the patients received. Data were sent on a standardized survey form via a national convenor to the coordinator. During the survey, 118 cases were reported, with 62 patients having disseminated disease, 31 acute pulmonary infection, chronic pulmonary infection in 6 and localized disease in 2 patients. For 17 patients, the diagnosis of histoplasmosis was incidental, usually secondary to investigations for lung cancer. Most patients had travelled to known endemic areas, but 8 patients (from Italy, Germany and Turkey) indicated that they had not been outside their countries of origin and hence these cases appear to be autochthonous. Notable observations during the survey were the reactivation of the disease up to 50 years after the initial infection in some patients and transmission of the infection by a transplanted liver. Itraconazole was the most commonly used therapy in both pulmonary and disseminated disease. The observation of autochthonous cases of disease suggests that the endemic area of histoplasmosis is wider than classically reported and supports continued surveillance of the disease throughout Europe.

AIDS-related Histoplasma capsulatum var. capsulatum infection: 25 years experience of French Guiana

OBJECTIVE

Histoplasma capsulatum var. capsulatum infection is a major AIDS-defining illness in French Guiana. Although it affects South and Central American countries, the number of published cases is low. We present the largest series of AIDS-related histoplasmosis. The aim of this work is to describe clinical features and to help optimize investigations in settings where antigen detection methods are not available.

DESIGN

Two hundred cases of AIDS-related histoplasmosis, diagnosed in the hospitals of French Guiana, were included retrospectively between 1982 and 2007.

RESULTS

At the time of diagnosis, 92% of patients did not receive highly active antiretroviral therapy. CD4 cell count was less than 100 cells/microl for 80% of them. Most patients had fever, lymphadenopathies, and pulmonary and digestive symptoms. Neurological signs and skin/mucosal locations were less common. Other opportunistic infections were associated in 36.6% of cases (mostly tuberculosis). In most of the patients, lactic dehydrogenase was at least four times the normal value, and there was a moderate increase of aspartate aminotransaminase but not alanine aminotransaminase levels. Bone marrow aspirations were useful, but cultures of liver and lymphadenopathy specimens were the most contributive. Following treatment initiation, 17.5% died within a month. Presumptive treatment was started before diagnostic confirmation in 14.3% of the cases.

CONCLUSION

In high prevalence settings, histoplasmosis often revealed AIDS in severely immunodeficient and poorly followed patients. In the absence of a quick sensitive technique, skin smear and fungal tissue cultures are contributive. Nevertheless, given the diagnostic delays and the poor prognosis, presumptive treatment with amphotericin B-containing regimens should be recommended when clinical and epidemiological contexts are evocative.

[Assessment of a quantitative PCR method for clinical diagnosis of imported histoplasmosis]

OBJECTIVE

Evaluation of the usefulness of a quantitative real-time polymerase chain reaction-based (RT-PCR) technique for clinical diagnosis of histoplasmosis.

METHODS

Primers and probes were designed on the basis of sequences from the ITS regions of ribosomal DNA of 20 clinical strains of Histoplasma capsulatum. LightCycler procedures (Roche Applied Science) were used with probes marked by fluorescence resonance energy transfer (FRET). Reproducibility, sensitivity, and specificity were analyzed. In addition, an internal control was designed to identify false negative results by PCR inhibition. The RT-PCR assay was tested in 22 clinical samples from 14 patients with proven histoplasmosis. In addition, 30 samples from patients with febrile neutropenia or mycoses other than histoplasmosis, and from healthy volunteers were analyzed as controls.

RESULTS

The limit of detection of the assay was 1 fg of genomic DNA per microl of sample. The PCR-based technique was reproducible and highly specific. Positive results were obtained in 11/14 (78.6%) patients and in 17/22 (77.3%) clinical samples. RT-PCR was positive in 100% of respiratory secretions and bone marrow samples, but only 70% of sera (p < 0.01). Mean fungal DNA value was 23.1 fg/microl in serum and 4.85 x 10(3) fg/microl in respiratory and bone marrow samples. RT-PCR results were positive in serum from three HIV patients for which antibody detection by immunodiffusion was negative. Specificity was 100%, since PCR results were negative for all the control samples.

CONCLUSION

Thes RT-PCR technique is a sensitive, specific method for early diagnosis of histoplasmosis, particularly when respiratory secretions or bone marrow samples are analyzed. The reliability is lower in serum, but it can be used as an additional, complementary technique to culture and serology in HIV patients.

American histoplasmosis in developing countries with a special focus on patients with HIV: diagnosis, treatment, and prognosis

PURPOSE OF REVIEW

Histoplasmosis due to Histoplasma capsulatum var capsulatum is a frequent systemic fungal infection in the Americas. Diagnostic and therapeutic options differ between North and South America. Disseminated histoplasmosis is an AIDS-defining infection. Prognostic factors of potentially severe presentations must be evaluated in order to facilitate the initial therapeutic choice.

RECENT FINDINGS

Patients with HIV with disseminated infections presenting with severe pulmonary and renal impairment have a poor prognosis. Cutaneous presentations are more frequent in HIV patients in South America than in North America. A murine model has shown that South American isolates have a greater virulence that North American isolates. These differences are due in part to diagnostic delays in resource-poor countries.

SUMMARY

Direct examination of May-Grünwald-Giemsa-stained smears or tissues in suspected histoplasmosis is a simple means of confirming the diagnosis in resource-poor settings. Studies of prognostic factors should further refine indication criteria to guide first-line treatment choice between amphotericin B and itraconazole. The association of tuberculosis and histoplasmosis is frequent in HIV patients and presents diagnostic and therapeutic challenges that may be difficult to resolve in resource-poor settings. It is important that affordable generic drugs for treating histoplasmosis be made widely available in resource-poor countries.

DIAGNOSIS OF HISTOPLASMOSIS

Endemic mycoses can be challenging to diagnose and accurate interpretation of laboratory data is important to ensure the most appropriate treatment for the patients. Although the definitive diagnosis of histoplasmosis (HP), one of the most frequent endemic mycoses in the world, is achieved by direct diagnosis performed by micro and/or macroscopic observation of Histoplasma capsulatum (H. capsulatum), serologic evidence of this fungal infection is important since the isolation of the etiologic agents is time-consuming and insensitive. A variety of immunoassays have been used to detect specific antibodies to H. capsulatum. The most applied technique for antibody detection is immunodiffusion with sensitivity between 70 to 100 % and specificity of 100%, depending on the clinical form. The complement fixation (CF) test, a methodology extensively used on the past, is less specific (60 to 90%). Detecting fungal antigens by immunoassays is valuable in immunocompromised individuals where such assays achieve positive predictive values of 96-98%. Most current tests in diagnostic laboratories still utilize unpurified antigenic complexes from either whole fungal cells or their culture filtrates. Emphasis has shifted, however, to clinical immunoassays using highly purified and well-characterized antigens including recombinant antigens. In this paper, we review the current conventional diagnostic tools, such as complement fixation and immunodiffusion, outline the development of novel diagnostic reagents and methods, and discuss their relative merits and disadvantages to the immunodiagnostic of this mycosis.