Disseminated atypical blastomycosis in two patients with AIDS

Blastomyces helicus, a New Dimorphic Fungus Causing Fatal Pulmonary and Systemic Disease in Humans and Animals in Western Canada and the United States

Background

Blastomyces helicus (formerly Emmonsia helica) is a dimorphic fungus first isolated from a man with fungal encephalitis in Alberta, Canada. The geographic range, epidemiology, and clinical features of disease are unknown.

Methods

We reviewed human and veterinary isolates of B. helicus identified among Blastomyces and Emmonsia isolates at the University of Alberta Microfungus Collection and Herbarium, University of Texas Health San Antonio’s Fungus Testing Laboratory, and Associated Regional and University Pathologists Laboratories. Isolates were selected based on low Blastomyces dermatitidis DNA probe values and/or atypical morphology. Species identification was confirmed for most isolates by DNA sequence analysis of the internal transcribed spacer with or without D1/D2 ribosomal RNA regions. Epidemiological and clinical data were analyzed.

Results

We identified isolates from 10 human and 5 veterinary cases of B. helicus infection; all were referred from western regions of Canada and the United States. Isolates remained sterile in culture, producing neither conidia nor sexual spores in the mycelial phase, but often producing coiled hyphae. Isolates were most frequently cultured from blood and bronchoalveolar lavage in humans and lungs in animals. Most infected persons were immunocompromised. Histopathological findings included pleomorphic, small or variably sized yeast-like cells, with single or multiple budding, sometimes proliferating to form short, branching, hyphal-like elements. Disease carried a high case-fatality rate.

Conclusions

Blastomyces helicus causes fatal pulmonary and systemic disease in humans and companion animals. It differs from B. dermatitidis in morphological presentation in culture and in histopathology, by primarily affecting immunocompromised persons, and in a geographic range that includes western regions of North America.

Emmonsia helica Infection in HIV-Infected Man, California, USA

Emmonsia-like fungi have rarely been reported from North America. We report a fatal case of E. helica infection in a man with advanced HIV infection from California, USA, who had progressive respiratory failure and a brain abscess.

Fatal fungemia due to Paracoccidioides lutzii

We report the first case of fungemia caused by Paracoccidioides lutzii in a 51-year-old male farm worker from the central-west region of Brazil. The fungus was isolated from blood cultures and the species was confirmed by phylogenetic identification. Despite specific treatment and intensive care, the patient died 39 days after admission.

Cutaneous alternariosis microscopically mimicking blastomycosis

A 57-year-old man status post several myocardial infarcts and heart transplantation presented with a slowly growing violaceous plaque on his lateral left knee at the site of prior minor trauma. A biopsy revealed a suppurative dermatitis with associated pseudocarcinomatous epithelial hyperplasia. There were multiple non-pigmented eosinophilic organisms with clear cytoplasmic halos within the infiltrate. A methenamine silver stain showed round to ovoid organisms of slightly variable size. Rare uni-polar budding, some of which was broad based, was apparent. A few short hyphae with indeterminate septa were also noted. Fontana-Masson, mucicarmine, Alcian blue and Fite stains were all negative. These findings suggested a diagnosis of blastomycosis. However, a fungal culture grew colonies of Alternaria species. Alternariosis has been previously shown to possess morphologic characteristics that can simulate other fungal infections. To our knowledge, a striking similarity to blastomycosis, as seen in our case, has not been previously reported. Dermatopathologists should be aware that alternariosis may mimic blastomycosis, especially when hyphal forms are rare or absent in tissue specimens. Culture is necessary for definitive classification.

Secondary Intracerebral Blastomycosis with Giant Yeast Forms

Secondary central nervous system (CNS) blastomycosis is an unusual manifestation of blastomycosis. We report a case of recurrent intracerebral blastomycosis that presented histopathologically with giant yeast-like cells and multinucleation that mimicked Coccidioides immitis. The yeast forms of Blastomyces dermatitidis usually range in size from 8 to 20 microm in diameter. Large or giant yeast forms (20-40 microm) are rare. The four cases previously reported in the literature involving giant yeast cell forms of B. dermatitidis are reviewed here. Intracerebral blastomycosis should be suspected in patients with signs and symptoms of CNS lesions and histories of primary blastomycosis, or treatment with corticosteroids, or comprised immune systems. The diagnosis should be confirmed by culture which presents typical biphasic microbiologic features.

Serological differences in three Blastomyces dermatitidis strains

Yeast phase lysate antigens, prepared from three isolates of Blastomyces dermatitidis (T-58, Tennessee dog; 48089, Zaire human; ERC-2, Wisconsin dog) were assayed for their ability to detect antibodies in human sera, dog sera and sera from rabbits immunized with each of the lysate antigens. The dog sera were from animals diagnosed with blastomycosis from various endemic regions in North America. T-58 and ERC-2 lysate antigens exhibited a high reactivity with the serum from dogs infected with blastomycosis; however, 48089 lysate showed low reactivity with the same sera. With the immunized rabbit sera, 48089 lysate was the only lysate with a high reactivity with the 48089 serum and it exhibited little reactivity with the heterologous sera. The T-58 and ERC-2 lysate antigens reacted minimally with the 48089 serum but reacted highly with both the T-58 and ERC-2 sera. The human sera were from individuals potentially exposed to B. dermatitidis while working on a prairie dog relocation project in Colorado. Remarkably, all three lysate antigens could detect antibodies in the individuals diagnosed with blastomycosis. This study indicated that there were serological differences in the 48089 Zaire lysate compared with the other lysate antigens and it may be designated serotype 2.

Disseminated cutaneous histoplasmosis in patients infected with human immunodeficiency virus

BACKGROUND

In the pre-AIDS era disseminated histoplasmosis was rare and the cutaneous manifestations thereof were reported infrequently. A range of unusual clinical manifestations of disseminated cutaneous histoplasmosis (DCH) in AIDS patients has been documented, but the cutaneous histopathological descriptions are short and incomplete. In addition, the histopathological spectrum of AIDS-associated DCH is poorly recognized.

METHODS

This is a prospective 32-month study of all HIV positive patients diagnosed with histoplasmosis in the Departments of Anatomical Pathology and Dermatology, Nelson R. Mandela School of Medicine and King Edward VIII Hospital, Durban, South Africa. Clinical distribution and morphology of the individual skin lesions and CD4+ lymphocyte counts in the peripheral blood were analysed in relation to the histopathological features of biopsied lesional tissue. Ultrastructural examination of tissue retrieved from the wax blocks of three cases that exhibited dermal karyorrhexis and collagen necrosis was undertaken. Fungal culture of lesional skin tissue was undertaken in all patients.

RESULTS

Twenty-one biopsies of papules (7), nodules (4), plaques (5), erythema multiforme-like lesions (2), vasculitic lesions (2) and exfoliative dermatitis (1) from 14 patients were examined. Of four biopsies (CD4 range: 120-128 cells/mm3) one and three demonstrated necrotizing and non-necrotizing granulomatous inflammation with a paucity of intrahistiocytic microorganisms. Seven biopsies (CD4 range: 2-56 cells/mm3) demonstrated diffuse dermal and intravascular accumulation of histiocytes densely parasitized by Histoplasma capsulatum var. capsulatum. Vasculitis, karyorrhexis or collagen necrosis was not present. Ten biopsies (CD4 range: 2-72 cells/mm3) demonstrated diffuse dermal karyorrhexis, collagen necrosis and interstitial, extracellular H. capsulatum var. capsulatum. Histiocytic disintegration and nuclear fragmentation and release of intact microorganisms and intact and ruptured lysosomes were identified ultrastructurally. Leucocytoclastic vasculitis was present in two biopsies of vasculitic clinical morphology. Microbiological culture confirmed histoplasmosis in all cases. Three patients died before treatment was commenced. Two patients died within the first two days of induction of therapy. Nine patients demonstrated dramatic healing of the cutaneous lesions.

CONCLUSIONS

Despite the clinicopathological spectrum of DCH and the attendant host immunocompromise, timely and appropriate treatment of DCH may be lifesaving and allows rapid healing of skin lesions. A high index of clinical suspicion and skin biopsies and culture are crucial for accurate diagnosis.

Molecular taxonomy and epidemiology of Blastomyces and Histoplasma species

Cladistic analysis of partial 26S rRNA sequences was used to estimate evolutionary distances among species and varieties of the dimorphic onygenalean genera Blastomyces, Coccidioides, Emmonsia, Histoplasma and Paracoccidioides. With the exception of Coccidioides, all genera were closely related, with about 5% base differences and even less (1-2%) between Blastomyces and Emmonsia. These data were supported by a teleomorph in the same genus Ajellomyces. In a phylogenic study of a wide range of ascomycete orders and families, Coccidioides immitis was found to be closest to Aphanoascus fulvescens and Chrysosporium keratinophilum, and to have relative distances to the remaining dimorphic genera (family Onygenaceae) similar to those of the dermatophytes (family Arthrodermataceae). The sequencing data were confirmed by genomic comparisons. All dimorphic genera had a nuclear DNA base composition in the same range of 46.6-47.3% G + C. The DNA melting curves of Blastomyces and Histoplasma strains showed irregularities that were ascribed to the presence of AT-rich stretches in satellite DNA rather than in mitochondrial DNA. Derivative profiles proved to be highly reproducible within regional populations and coincided with differences in clinical behaviour of each species. Blastomyces dermatitidis generated two kinds of curves, corresponding to the geographically distinct serotypes 1 and 2. The African type (serotype 2) was characterized by a classical sigmoidal melting curve similar to that for all strains of Coccidioides, Emmonsia and Paracoccidioides. In contrast, the American type (serotype 1) contained satellite DNA (27% G + C). A rRNA base difference of 1.5% was observed between geographical types, a value slightly higher than that noted between Histoplasma capsulatum and its variety farciminosum (0.9%). All three H. capsulatum varieties presented irregularities in their DNA melting curves. The molecular data support the recognition of two of them as agents of blastomycosis and the assignment of more than one species and two varieties to the genus Emmonsia.

Disseminated blastomycosis and acquired immunodeficiency syndrome: a case report and ultrastructural study

A 42-year-old, African-American man presented with a 2-month history of weight loss and fever for 2 weeks. Presumptive diagnoses of human immunodeficiency virus infection (HIV) and acquired immunodeficiency syndrome were made on the basis of a CD4 lymphocyte count of 23 lymphocytes/mL. Chest x-ray revealed right paratracheal adenopathy and a miliary pattern. The etiology of the patient's pulmonary infection was not known, but tuberculosis was an important consideration. Over 5 days, the pulmonary infection progressed and was complicated by acute respiratory distress syndrome (ARDS), septic shock, and death, despite vigorous antibiotic and supportive therapy. Serologic tests for HIV infection were reported as positive after the patient's demise. The etiology of the patient's pulmonary infection, ARDS, and sepsis was not known until autopsy study revealed enumerable yeast-like cells of Blastomyces dermatitidis in the extensively consolidated lungs and in disseminated foci of infection in most other major organs. Diffuse alveolar damage was closely associated with the pulmonary blastomycosis. Electron microscopic study of the yeast-like cells of B. dermatitidis in the autopsy lung obtained and fixed 5 days after the patient's death revealed excellent preservation of viable organisms.