Blastomycosis

Spontaneous resolution of blastomycosis symptoms caused by B. dermatitidis

Given the propensity of blastomycosis to disseminate or reoccur and the inability to predict which infections will experience severe manifestations, nearly all cases of blastomycosis are treated. Although, spontaneous resolution of symptoms is referred to generally in the literature, to our knowledge an individual case of this has not been previously reported. We report the spontaneous resolution of blastomycosis symptoms in a 40 year-old Caucasian male.

Dynamic interplay among monocyte-derived, dermal, and resident lymph node dendritic cells during the generation of vaccine immunity to fungi

Early innate events that enable priming of antifungal CD4 T cells are poorly understood. We engineered an attenuated fungal vaccine with a model epitope, EalphaRFP, to track vaccine immunity to Blastomyces dermatitidis during yeast recognition, antigen presentation, and priming of naive T cells. After subcutaneous injection of the vaccine, monocyte-derived inflammatory dendritic cells (DCs) are the earliest and largest population that associates with yeast, carrying them into the draining lymph nodes. Despite marked association with yeast, these DCs fail to display surface peptide:MHC complexes or prime naive T cells. Instead, the ability to display antigen and prime CD4 T cells resides with lymph node-resident DCs after antigen transfer from immigrant DCs and with skin migratory DCs. Our work reveals the dynamic interplay among distinct DC subsets that prime naive CD4 T cells after yeast are injected in the skin and discloses the cellular elements underlying vaccine-induced immunity to fungi.

Clinical and laboratory update on blastomycosis

Blastomycosis is endemic in regions of North America that border the Great Lakes and the St. Lawrence River, as well as in the Mississippi River and Ohio River basins. Men are affected more often than women and children because men are more likely to participate in activities that put them at risk for exposure to Blastomyces dermatitidis. Human infection occurs when soil containing microfoci of mycelia is disturbed and airborne conidia are inhaled. If natural defenses in the alveoli fail to contain the infection, lymphohematogenous dissemination ensues. Normal host responses generate a characteristic pyogranulomatous reaction. The most common sites of clinical disease are the lung and skin; osseous, genitourinary, and central nervous system manifestations follow in decreasing order of frequency. Blastomycosis is one of the great mimickers in medicine; verrucous cutaneous blastomycosis resembles malignancy, and mass-like lung opacities due to B. dermatitidis often are confused with cancer. Blastomycosis may be clinically indistinguishable from tuberculosis. Diagnosis is based on culture and direct visualization of round, multinucleated yeast forms that produce daughter cells from a single broad-based bud. Although a long course of amphotericin B is usually curative, itraconazole is also highly effective and is the mainstay of therapy for most patients with blastomycosis.

The evolution of sex: a perspective from the fungal kingdom

Sex is shrouded in mystery. Not only does it preferentially occur in the dark for both fungi and many animals, but evolutionary biologists continue to debate its benefits given costs in light of its pervasive nature. Experimental studies of the benefits and costs of sexual reproduction with fungi as model systems have begun to provide evidence that the balance between sexual and asexual reproduction shifts in response to selective pressures. Given their unique evolutionary history as opisthokonts, along with metazoans, fungi serve as exceptional models for the evolution of sex and sex-determining regions of the genome (the mating type locus) and for transitions that commonly occur between outcrossing/self-sterile and inbreeding/self-fertile modes of reproduction. We review here the state of the understanding of sex and its evolution in the fungal kingdom and also areas where the field has contributed and will continue to contribute to illuminating general principles and paradigms of sexual reproduction.

Primary blastomycosis of oral cavity

BACKGROUND

Blastomycosis is an uncommon male-predominant disease caused by the fungus Blastomyces dermatitidis. The lungs are most commonly affected, and other organs are usually involved by dissemination. Clinical feature and pathohistologic findings are similar to the appearance of squamous cell carcinoma.

METHODS AND RESULTS

A 52-year-old male patient who has lived as a farmer on the countryside in Argentina for 35 years presented with an initial histopathologic diagnosis of a squamous cell carcinoma of the right lower jaw. There was no history of pulmonary disease, in particular fever, coughing, or hemoptysis. Final pathohistologic evaluation after resection revealed B. dermatitidis infection. This article presents the first described case of oral manifestation of B. dermatitidis infection in Switzerland.

CONCLUSIONS

Manifestation of blastomycosis in oral tissue can mimic the feature of a squamous cell carcinoma and can therefore be a diagnostic pitfall that head and neck surgeons and a pathologist should be aware of.

Blastomycosis

Blastomycosis is an endemic mycoses in the central United States caused by a dimorphic fungus, Blastomyces dermatitidis, that exists in nature in mycelial phase and converts to yeast phase at body temperature. The organism may produce epidemics of infection following a point source of infection or sporadic endemic infection. Blastomycosis can be a subclinical illness with subsequent protection against progressive infection afforded by cellular immune mechanisms, but it may present with progressive disease with either pulmonary or extrapulmonary disease or both. Itraconazole has been shown to be the drug of choice for both infections, except in cases of life-threatening infection when amphotericin B should be used.

Blastomycosis of the Vocal folds with Life-Threatening upper Airway Obstruction: A Case Report

Blastomycosis is a chronic fungal disease that primarily affects the lower respiratory tract. The acute inflammatory phase of the primary pulmonary infection is characterized by a lymphohematogenous spread to extrapulmonary sites, especially the skin. The presence of disseminated infection with Blastomyces dermatitidis in the larynx is unusual. In areas of the United States where this fungus is endemic, failure to consider laryngeal involvement might lead to inappropriate therapy and thus worsening inflammation and airway compromise.

Cutaneous lesions showing giant yeast forms of Blastomyces dermatitidis

BACKGROUND

The yeast forms of Blastomyces dermatitidis usually range from 8 to 15-20 micro m in diameter. Larger yeast forms have previously been reported only twice in immunosuppressed patients. In both patients these large forms were seen within the lung.

CASE REPORT

We present a 14-year-old cardiac transplant patient, who presented 36 days following his transplantation with acute respiratory distress followed a few days later by erythematous cutaneous papules.

RESULTS

Biopsy of a skin lesion showed yeast forms, some greater than 40 micro m in diameter, within and surrounding dermal vessels. Cultures later grew Blastomyces dermatitidis.

CONCLUSIONS

To our knowledge this is the first reported case of giant forms of Blastomyces dermatitidis within the skin. With increased iatrogenic immunosuppression, we may expect to see more diverse morphologic forms with deep fungal infections.

Genitourinary fungal infections: a therapeutic conundrum

Fungi cause 8% of nosocomial infections. This is caused, in part, by the increasing pool of immunocompromised patients. Elderly, transplant and HIV patients, as well as premature infants, have become prime candidates for invasive fungal infections. The widespread use of broad spectrum antibiotics plays a role. Utilisation of appropriate antifungal treatment modalities requires an understanding of the pathogenesis of infection. This is a challenging problem as fungi can cause different clinical manifestations that depend on the type of fungal species and patient response to the infection. Although Candida spp. are the most frequent pathogen, other species such as Aspergillus and Cryptococcus have become major pathogens. Environmental fungi which include Blastomyces, Coccidioides and Histoplasma have become more aggressive in the vulnerable patient. The genitourinary system can be a source or target of disseminated fungal infection. Diagnosis depends on clinical awareness, utilisation of appropriate diagnostic modalities, imaging modalities and a thorough clinical assessment. The treatment of primary (Blastomyces, Coccidioides, Histoplasma) infection generally requires amphotericin B (AmpB). The opportunistic infections (Aspergillus, Cryptococcus and Candida) may respond to the triazoles although AmpB remains the 'gold standard'. Infections caused by Candida spp. represents the greatest challenge to the clinician. The presence of Candida spp. in the urine may indicate colonisation or infection. Untreated, Candida can remain as a 'saprophyte' or develop ascending infection, sepsis or death. The prophylactic use of fluconazole may in itself result in resistant infection, hence the 'conundrum'.

Cervical manifestation of blastomycosis

Blastomycosis is a common systemic fungal infection in which the physical and radiographic findings appear far more serious than the subjective signs and symptoms. Although blastomycosis of the head and neck is often difficult to diagnose, clues in the patient's history and a few laboratory tests can establish the diagnosis. Involvement of the skin and soft tissues provides an unusual opportunity for direct access to the organism for culture and pathologic diagnosis. We present a case of blastomycosis presenting in a single abscessed cervical lymph node. The diagnosis was established by fine-needle aspiration of the cervical mass. The primary lung disease was confirmed by chest radiography and computed tomography. The clinical and pathologic features of the disease are discussed. [Editorial comment: Pulmonary blastomycosis may present with cervical adenopathy. This article demonstrates the potential value of fine needle aspiration in establishing this diagnosis.]

Chronic paronychia, osteomyelitis, and paravertebral abscess in a child with blastomycosis

Blastomycosis is an unusual fungal infection in children. It is often a chronic infection characterized by granulomatous and suppurative lesions. Clinical manifestations include either pulmonary findings or disseminated disease. Disseminated blastomycosis usually begins with a lung infection that spreads to the skin, bones, and central nervous system. This is a case report of a child with chronic blastomycosis presenting with chronic paronychia, fever, cough, malaise, and back pain. The child underwent surgical drainage of a paravertebral abscess and administration of intravenous amphotericin B. He was discharged in good condition on oral therapy with ketoconazole. The literature on blastomycosis, with particular emphasis on clinical presentations and management, is reviewed. When the history and physical examination suggest a chronic granulomatous or disseminated disease, such as tuberculosis, the physician must include blastomycosis in the differential.

Canine antibody response to Blastomyces dermatitidis WI-1 antigen

OBJECTIVE

To assess whether dogs with blastomycosis produce antibodies against the WI-1 and A-antigens of Blastomyces dermatitidis and whether the antibodies are useful in serodiagnosis.

SAMPLE POPULATION

359 serum samples obtained from 245 dogs.

PROCEDURE

233 samples from 122 dogs with blastomycosis, and 1 sample each from 24 dogs with suspected blastomycosis, 51 control dogs without infection, and 48 healthy dogs from an enzootic region were obtained. Antibodies against WI-1 antigen were detected by radioimmunoassay (RIA). Serum samples were tested in parallel for antibodies against the A-antigen of B dermatitidis by commercial agar-gel immunodiffusion (AGID) in a reference laboratory.

RESULTS

Antibodies were detected in 92% of infected dogs by RIA and in 41 % by AGID. For 29 serum samples that were obtained 11 to 1,545 days after diagnosis, antibodies were detected in 92% of samples by RIA and 7% by AGID. For 93 serial serum samples from 29 dogs with blastomycosis, the mean anti-WI-1 titer was 1:18,761 at the time of diagnosis, and decreased to a mean of 1:1,338 by 210 days after treatment was initiated. Of 24 dogs with suspected infection, antibodies were detected in 67% by RIA and 33% by AGID. Control dogs without blastomycosis had no detectable antibodies in either assay. Thus, sensitivity was 92% for RIA and 41 % for AGID, and specificity was 100% for both tests.

CONCLUSIONS AND CLINICAL RELEVANCE

Anti-WI-1 antibodies are readily detected by RIA in dogs with blastomycosis. Titers become high, decline during treatment, and persist for months. Anti-A antibodies are sometimes detected with AGID, but these decrease quickly.

Diploid strains of the pathogenic basidiomycete Cryptococcus neoformans are thermally dimorphic

Cryptococcus neoformans is an opportunistic human pathogenic fungus with a defined sexual cycle. Clinical and environmental isolates of C. neoformans are haploid, and the diploid stage of the lifecycle is thought to be transient and unstable. In contrast, we find that diploid strains are readily obtained following genetic crosses of congenic MATalpha and MATa strains. At 37 degrees C, the diploid strains grow as yeast cells with a single nucleus that is larger than a haploid nucleus, contains a 2n content of DNA by FACS analysis, and is heterozygous for the MATalpha and MATa loci. At 24 degrees C, these diploid self-fertile strains filament and sporulate, producing recombinant haploid progeny in which meiotic segregation has occurred. In contrast to dikaryotic filament cells that are typically linked by fused clamp connections during mating, self-fertile diploid strains produce monokaryotic filament cells with unfused clamp connections. We also show that these diploid strains can be transformed and sporulated and that an integrated selectable marker segregates in a mendelian fashion. The diploid state could play novel roles in the lifecycle and virulence of the organism and can be exploited for the analysis of essential genes. Finally, the observation that dimorphism is thermally regulated suggests similarities between the lifecycle of C. neoformans and other thermally dimorphic human pathogenic fungi, including Histoplasma capsulatum, Blastomyces dermatitidis, Coccidioides immitis, Paracoccidioides brasiliensis, and Sporothrix schenkii.

Fungal infections of the genitourinary system: manifestations, diagnosis, and treatment

There is an increasing pool of immunocompromised patients who are at an increased risk to fungi infections, which now cause 8% of nosocomial infections. Premature infants and elderly, transplant, and HIV patients are prime candidates for invasive fungal infections. The genitourinary system can be a source or target of disseminated fungal infection. Although candidal species are the most frequent pathogen, other species such as aspergila, cryptoccoccus have become major pathogens. "Environmental fungi," which include blastomyces, coccidioides and histoplasma, have become more aggressive in the vulnerable patient.

Serious waterborne and wilderness infections

Serious waterborne and wilderness infections are common and usually treatable if diagnosed early. The differential diagnosis for these infections requires a careful and thorough history and physical examination. Common clinical presentations include acute febrile illnesses, altered mental status, diarrhea, or pneumonia. Pathogens causing serious infections include bacteria, fungi, viruses, and protozoa. Epidemiologic help can be obtained from local or state health departments as well as the Centers for Disease Control.

Purification in quantity of the secreted form of WI-1: a major adhesin on Blastomyces dermatitidis yeasts

WI-1, a 120-kDa adhesin on Blastomyces dermatitidis, binds the yeast to macrophages and is a major target antigen of immune recognition in acquired resistance to the fungus. In past studies, WI-1 has been purified by extracting the protein from the yeast cell wall, which yields microgram quantities for biological assays. We report a strategy for generating and purifying the secreted form of WI-1 in quantity. Yeasts of B. dermatitidis ATCC strain 60636 cultured in HMM medium were found to secrete 10 microg/ml of WI-1 into a supernate relatively free of other medium and yeast components. Using a two-step method of ion exchange and hydrophobic interaction chromatography, we achieved a 7.1-fold purification of WI-1. Purified WI-1 was sequenced at the N-terminus which revealed that the secreted protein exists in two different forms. In functional assays, purified WI-1 also retained its adhesivity for human macrophages, and its antigenicity in binding anti-WI-1 antibodies and stimulating T-cells to proliferate, but it lost some capacity to elicit delayed-type hypersensitivity in mice. These findings advance our understanding of the WI-1 adhesin/antigen and our ability to express and purify WI-1 in quantity and will permit a study of the relationship between three-dimensional structure and activity of the molecule.

Blastomycosis-induced respiratory failure: the successful application of continuous positive airway pressure

A patient diagnosed with pulmonary blastomycosis was seen initially by her primary care physician for severe pain in her right elbow and was treated with steroid therapy and analgesics. She also had been treated for chronic cough and congestion for approximately 2 months before admission. She showed no improvement at home. She was hospitalized for right epicondylitis, and progressively worsening restrictive pulmonary symptoms developed, including hypoxemia and dyspnea. She was transferred to the intensive care unit and treated with mask continuous positive airway pressure (CPAP) and intravenous amphotericin B. Despite worsening hypoxemia, successful management of oxygenation was achieved with CPAP, averting the need for intubation and mechanical ventilation. This case demonstrates the usefulness of CPAP in infectious disorders that create restrictive lung impairment.

Cutaneous manifestations of systemic mycoses

Systemic fungal diseases are primary pulmonary diseases caused by the dimorphic fungal pathogens, Blastomyces dermatitides, Coccidioides immitis. Histoplasma capsulatum, or Paracoccidioides brasiliensis. Infection occurs after inhalation of the infectious form of the fungus and may be acute, self-limited, or subclinical. Primary cutaneous infection occurs only after traumatic implantation of the fungus and is unusual. Erythema nodosum or erythema multiforme may accompany the acute form of the disease. Other cutaneous manifestations represent disseminated disease and, as such, require systemic antifungal therapy. Because cutaneous lesions have occurred coincidentally with other cutaneous pathologies, emphasis should be placed on a complete clinical history, physical examination, and diagnosis by histopathology and culture.

Genomic cloning, characterization, and functional analysis of the major surface adhesin WI-1 on Blastomyces dermatitidis yeasts

WI-1 is a 120-kDa surface protein adhesin on Blastomyces dermatitidis yeasts that binds CD18 and CD14 receptors on human macrophages. We isolated and analyzed a clone of genomic WI-1 to characterize this key adherence mechanism of the yeast. The 9.3-kilobase insert contains an open reading frame of 3438 nucleotides and no introns. The amino acid sequence of native WI-1 matches the deduced sequence of genomic WI-1 at positions 757-769, 901-913, and 1119-1138, demonstrating the cloned gene is authentic WI-1. The complete coding sequence has 30 highly conserved repeats of 24 amino acids arrayed in tandem in two noncontiguous regions of the protein. The repeat sequence is homologous to the Yersiniae adhesin invasin, the C terminus displays an epidermal growth factor-like domain, and the N terminus has a short hydrophobic sequence that may be a membrane-spanning domain. The tandem repeats are predicted to be at the exposed surface of the protein, thereby explaining the adhesive properties of WI-1. The WI-1 promoter contains a CAAT box (nucleotide positions 2287-2290), TATA box (2380-2385), and CT motif (2399-2508). Transcription is initiated within the CT motif at nucleotide 2431. A 5.5-kilobase subclone containing the full coding sequence of WI-1 was expressed as a histidine-tagged fusion protein in Escherichia coli. Recombinant WI-1 has the expected molecular mass of 120 kDa, is strongly recognized in Western blots by rabbit anti-WI-1 antiserum, and binds human macrophage receptors in the same manner as native WI-1. This work clarifies a key adherence mechanism of B. dermatitidis and will permit further analysis of WI-1-mediated attachment to host cells, receptors, and extracellular matrix.

Endemic mycoses in AIDS: a clinical review

Histoplasmosis and coccidioidomycosis are serious opportunistic infections in patients with AIDS who reside in areas of endemicity of the United States and Central and South America. Blastomycosis, although less common, also must be recognized as an opportunistic infection in patients with AIDS. Prompt diagnosis requires knowledge of the clinical syndromes and diagnostic tests as well as a high index of suspicion. Histoplasmosis and blastomycosis respond well to antifungal treatment, but relapse is common without chronic suppressive therapy. Improvements in treatment are needed in coccidioidomycosis. Research is needed to identify preventive strategies for patients at risk. These strategies may include use of prophylactic antifungal therapy or vaccination.

Reactivation and dissemination of blastomycosis complicating Hodgkin's disease: a case report and review of the literature

Patients presenting with Hodgkin's disease (HD) may show lung involvement characterized by contiguous spread from ipsilateral hilar lymph nodes. Lung consolidation or noncontiguous pulmonary involvement makes an alternative diagnosis more likely. This report describes a patient with HD in whom concurrent pulmonary blastomycosis was recognized only after chemotherapy had started and dissemination had occurred. Although Blastomyces dermatitidis may behave as an opportunist pathogen, there are no previous reports of blastomycosis in patients with HD. Undiagnosed active opportunistic infection at the time of diagnosis of HD may complicate staging as well as treatment. Biopsy of lung lesions with stain and culture for opportunistic pathogens should be considered in patients with newly diagnosed HD disease and atypical patterns of lung involvement.