Endogenous activation in blastomycosis

A 66-year-old woman with fever, cough, and a tongue lesion

A 66-year-old woman presented with acute onset of fever, chills, and productive cough associated with right-sided chest pain. During a recent hospitalization for dyspnea, she had been diagnosed with Coombs-positive autoimmune hemolytic anemia and had been taking a tapering dose of prednisone starting approximately 6 weeks prior to admission. In the interim, her dyspnea had resolved on treatment with steroids. At the time of presentation, her prednisone dose was 40 mg. Additional medical history included VTE, for which the patient was receiving anticoagulation therapy, and steroid-induced diabetes mellitus. Many years earlier, she had been treated for TB in her home country. The patient had immigrated to Queens, New York, from a Nepalese village 8 years prior. While still in Nepal, she had worked on a farm and had been in close proximity to cows. In Queens, she lived with her family in a house with a small garden but had no pets. Recent travel included a visit to Nepal 9 months ago and a trip to Syracuse, New York, one month prior to presentation. She was a never smoker and did not consume alcohol.

The unappreciated intracellular lifestyle of Blastomyces dermatitidis

Blastomyces dermatitidis, a dimorphic fungus and the causative agent of blastomycosis, is widely considered an extracellular pathogen, with little evidence for a facultative intracellular lifestyle. We infected mice with spores, that is, the infectious particle, via the pulmonary route and studied intracellular residence, transition to pathogenic yeast, and replication inside lung cells. Nearly 80% of spores were inside cells at 24 h postinfection with 10(4) spores. Most spores were located inside of alveolar macrophages, with smaller numbers in neutrophils and dendritic cells. Real-time imaging showed rapid uptake of spores into alveolar macrophages, conversion to yeast, and intracellular multiplication during in vitro coculture. The finding of multiple yeast in a macrophage was chiefly due to intracellular replication rather than multiple phagocytic events or fusion of macrophages. Depletion of alveolar macrophages curtailed infection in mice infected with spores and led to a 26-fold reduction in lung CFU by 6 d postinfection versus nondepleted mice. Phase transition of the spores to yeast was delayed in these depleted mice over a time frame that correlated with reduced lung CFU. Spores cultured in vitro converted to yeast faster in the presence of macrophages than in medium alone. Thus, although advanced B. dermatitidis infection may exhibit extracellular residence in tissue, early lung infection with infectious spores reveals its unappreciated facultative intracellular lifestyle.

Seasonal variations in the clinical presentation of pulmonary and extrapulmonary blastomycosis

Blastomycosis is a granulomatous infection caused by the thermally dimorphic fungus, Blastomyces dermatitidis, for which seasonal variation has been proposed. We conducted a retrospective review of medical records of 324 patients with blastomycosis in Manitoba and northwestern Ontario. The average age of patients at the time of diagnosis was 39+/-20 (range, 0-85) years. Symptoms referable to blastomycosis were first noted in the autumn and winter (September to February) by 63% of the patients. The seasonal distribution of cases was different for localized pulmonary infection than the disseminated disease (P<0.0001). For localized lung disease, the peak incidence of symptom onset occurred in the autumn, and lowest incidence in the spring; one half (50%) of the patients with diffuse lung disease had onset of symptoms in the spring months and a few (11%) cases occurred during the summer. We noted a distinct seasonal variation in the clinical presentation of blastomycosis. The observed pattern suggests that summer environmental exposure and acquisition of the infection results in an early (1-6 months) localized pneumonia in the majority of cases, followed by later (4-9 months) reactivation or slow progression of asymptomatic infection resulting in isolated extrapulmonary or disseminated hematogenous disease in the minority.

Clinical characteristics and outcomes in patients with pulmonary blastomycosis

BACKGROUND

Blastomycosis is an uncommon granulomatous infection caused by the thermally dimorphic fungus Blastomyces dermatitidis. The most frequent clinical infections involve the lung, skin, and bone. Pulmonary manifestations range from asymptomatic self-limited infection to severe diffuse pneumonia causing respiratory failure.

OBJECTIVES

To establish the clinical characteristics and outcomes of patients with pulmonary blastomycosis diagnosed at hospitals in Manitoba and northwestern Ontario, Canada.

METHODS

A retrospective review of medical records was done for 318 patients with blastomycosis in these regions.

RESULTS

The majority of patients were Caucasian (198 (62.5%) patients), male (193 (61%) patients), and residents of Ontario (209 (65.7%) patients). Most patients were treated in an inpatient hospital ward (266 (84%) patients) and survived (294 (92%) patients). Pulmonary involvement, either alone or associated with other sites, was present in 296 (93%) of the 318 patients; 22 (7%) patients had no evidence of pulmonary blastomycosis. The majority of patients had localized lung disease (1-3 quadrants on chest radiograph involved; 225 (82%) patients). Of 294 (92%) patients requiring hospitalization, 266 (90%) patients received all inpatient care on a general medical ward; 28 (10%) patients received some care in the intensive care unit (ICU). Factors associated with ICU admission included diffuse pulmonary disease (four quadrants involved on chest radiograph), diabetes, and prior use of antimicrobial therapy. Twenty-four (8%) patients died, and multivariate analysis showed that older age and Aboriginal ethnicity were the significant risk factors for death from blastomycosis.

CONCLUSION

Blastomycosis is a cause of serious, potentially life-threatening pulmonary infection in this geographic region.

Fungal Infections

The incidence of invasive fungal infections has increased dramatically over the past two decades, mostly due to an increase in the number of immunocompromised patients.1–4 Patients who undergo chemotherapy for a variety of diseases, patients with organ transplants, and patients with the acquired immune deficiency syndrome have contributed most to the increase in fungal infections.5 The actual incidence of invasive fungal infections in transplant patients ranges from 15% to 25% in bone marrow transplant recipients to 5% to 42% in solid organ transplant recipients.6,7 The most frequently encountered are Aspergillus species, followed by Cryptococcus and Candida species. Fungal infections are also associated with a higher mortality than either bacterial or viral infections in these patient populations. This is because of the limited number of available therapies, dose-limiting toxicities of the antifungal drugs, fewer symptoms due to lack of inflammatory response, and the lack of sensitive tests to aid in the diagnosis of invasive fungal infections.1 A study of patients with fungal infections admitted to a university-affiliated hospital indicated that community-acquired infections are becoming a serious problem; 67% of the 140 patients had community-acquired fungal pneumonia.8

Blastomycosis of Bones and Joints

A retrospective study of 45 patients hospitalized with blastomycosis of bones or joints revealed 41 cases of osteomyelitis and 12 cases of septic arthritis. The majority were men (35 [78%] patients) and non-Aboriginal (32 [71%] patients). Median time from the onset of symptoms to hospitalization was shorter in women than men (male, 48 d; female, 14 d; P < 0.02), and shorter for Aboriginals than non-Aboriginals (non-Aboriginal, 50 d; Aboriginal, 19 d; P < 0.04). Cutaneous disease was present in 33 (73%) patients, and lung involvement was present in 29 (64%) patients. The most common osseous sites of involvement were the lower limb and axial skeleton. Common orthopaedic symptoms of bone lesions included bone pain in 42 (78%) patients, swelling in 32 (59%) patients, and soft tissue abscesses in 21 (39%) patients. Joint infection (12 patients) manifested as a monoarticular arthropathy presenting with effusion in 9 (75%) patients, pain in 8 (67%) patients, and decreased range of motion in 5 (42%) patients. Osseous blastomycosis can mimic bacterial infection and should be included in the differential diagnosis of bone and joint infection in patients who have visited or who live in geographic regions where B dermatitidis is endemic.

Blastomycosis in a young African man presenting with a pleural effusion

Blastomyces dermatitidis is a dimorphic fungus endemic to north-western Ontario, Manitoba and some parts of the United States. The fungus is also endemic to parts of Africa. Pulmonary and extrapulmonary findings of a 24-year-old African man who presented with weight loss, dry cough and chronic pneumonia not resolving with antibiotic treatment are presented. The unusual occurrence of pulmonary blastomycosis associated with skin lesions and a moderate pleural effusion is reported.

Chronic disseminated cutaneous blastomycosis in an 11-year old, with a brief review of the literature

Chronic disseminated cutaneous blastomycosis is rare in children. We discuss an 11-year-old immunocompetent boy who presented with a history of persistent and multiple skin lesions of >1 year's duration. These lesions proved to be secondary to chronic Blastomyces dermatitidis infection. Complete resolution of clinical disease occurred after a 6-month course of oral itraconazole. We also present a brief review of the literature focusing on the epidemiology, manifestations, diagnosis, and treatment of pediatric blastomycosis.

Using local epidemiology to make a difficult diagnosis: a case of blastomycosis

An otherwise well 21-year-old man from Northwestern Ontario presented to our emergency department in Winnipeg, Manitoba, with a 2-month history of cough, progressively increasing dyspnea, hemoptysis and a 15-kg weight loss. His symptoms were worsening despite antibiotic treatment for presumed bacterial pneumonia. His past history included work as a seasonal labourer clearing brush. He was not hypoxic on room air, but his chest radiograph revealed a miliary pattern and bilateral infiltrates. A Mantoux test for tuberculosis was non-reactive, and the sputum gram stain was unremarkable. Empiric therapy was initiated for blastomycosis and the diagnosis was confirmed with a calcofluor stain of the sputum. Although blastomycosis is rare in most regions in North America, there is an unusually high incidence of blastomycosis in Northwestern Ontario. This case highlights the intolerance and utility of knowledge of the local epidemiology in establishing difficult diagnoses of regional importance, such as fungal pneumonias.

Blastomycosis

Blastomycosis is a relatively uncommon disease, even in its endemic region. The clinical course and symptoms are highly variable; patients may be asymptomatic or present with severe, fulminant disease. Antifungal agents are effective against pulmonary and disseminated disease, but relapses and reactivation can occur. The radiographic findings are nonspecific, and patients are often assumed to have bacterial pneumonia, malignancy, tuberculosis, or sarcoidosis before the correct diagnosis is made.

Overwhelming pulmonary blastomycosis associated with the adult respiratory distress syndrome

BACKGROUND AND METHODS

Few cases of overwhelming pulmonary blastomycosis associated with the adult respiratory distress syndrome have been reported. We describe 10 patients with this condition who were treated at one center in Wisconsin.

RESULTS

All 10 patients presented with fever, cough, and dyspnea; radiographic evidence of diffuse pulmonary infiltrates; and marked impairment of oxygenation. The mean alveolar-arterial oxygen gradient was 616 mm Hg. Six of the patients had no underlying disease associated with altered immunity, and two had no recent exposure to environmental reservoirs of Blastomyces dermatitidis. In all 10 patients, large numbers of broad-based budding yeasts were seen on microscopical examination of tracheal secretions. All patients were treated with intravenous amphotericin B (0.7 to 1.0 mg per kilogram per day). Of the five survivors, four received full doses of amphotericin B in the first 24 hours, and four required mechanical ventilatory support for 7 to 151 days. Long-term follow-up of three survivors showed good recovery of pulmonary function.

CONCLUSIONS

Overwhelming infection with B. dermatitidis can cause diffuse pneumonitis and the adult respiratory distress syndrome, even in immunocompetent hosts. With prompt diagnosis by microscopical examination of tracheal secretions, intensive therapy with amphotericin B, and ventilatory support, good recovery of pulmonary function is possible.

Fulminant blastomycosis with blastomycotic infection of a cerebral glioma. Light microscopic and ultrastructural observations

Except for isolated case reports, blastomycosis has not been identified as a significant problem in immunosuppressed patients. We describe an unusual case with blastomycotic infection of a cerebral glioma in a 56-year-old man who underwent radiotherapy for his tumor and died of fulminant blastomycotic pneumonia. This is believed to be the first reported case of Blastomyces dermatitidis infection of a cerebral glioma. The light microscopic and ultrastructural features of B. dermatitidis, the giant forms of which were encountered in our patient, are described, and thr role of immunosuppression due to steroid therapy in the pathogenesis of this fulminant infection are reviewed.

Roentgenologic features of pulmonary blastomycosis

In 35 cases of pulmonary blastomycosis, the roentgenologic features were as follows: consolidation 26%, mass 31%, intermediate-sized nodules 6%, miliary pattern 11%, solitary cavity 9%, fibrotic and cavitary changes 6%, interstitial pattern 6%, diffuse alveolar involvement 3%, and mixed alveolar and interstitial infiltrate 3%. All symptomatic cases of consolidation were acute (symptoms for less than 1 month), and most were in young patients (mean age, 34 years). Consolidation constituted 58% of the acute cases in this series. Two of the nine cases of consolidation were asymptomatic epidemic cases detected by screening. A pulmonary mass was the most common initial manifestation in this series; it tended to occur in patients with chronic symptoms (more than 1 month). The mass was considered suggestive enough of bronchogenic carcinoma to necessitate resection in 55% of cases. The military form of pulmonary blastomycosis occurred in older patients with disseminated disease. Fibrotic and cavitary disease was chronic in nature. The presence of intermediate-sized nodules elsewhere in the lung proved to be a helpful diagnostic finding in several patients with consolidation, mass, or cavitary disease. Hilar adenopathy, postinfectious calcification, chest wall invasion, and pleural effusion occurred infrequently or not at all in this series.

Blastomycosis

Blastomycosis is the least understood of the major endemic mycoses in North America. The fungus exists in the soil in its mycelial form, and when the proper growth conditions exist growth and spore formation will occur. When microfici containing the growing mycelium of blastomyces are disturbed, an infecting aerosol is formed. The spores are inhaled and eventually settle in the alveoli where multiplication by binary fission occurs. Following development of cell-mediated immunity the infection is localized in the lung. During the pre-immune phase of the infection spread to extrapulmonary sites may occur. Most common sites of involvement include the skin, bones, prostate and central nervous system. Pulmonary disease may resolve spontaneously or progress. Treatment is required for progressive pulmonary illness and all episodes of extrapulmonary disease. For life-threatening blastomycosis or blastomycosis of the central nervous system amphotericin B is the treatment of choice, while ketoconazole is an excellent alternative for patients who are not critically ill or have no central nervous system involvement.

Localized oral blastomycosis mimicking actinomycosis

A case of blastomycosis limited to the oral cavity is presented. The disease apparently originated in the mandible and eroded into the oral cavity. Secondary bacterial infection of the sinus tracts resulted in a clinical picture that mimicked cervicofacial actinomycosis. Appropriate microbiologic studies, including culture confirmation of the causative organism, were necessary to establish a definitive diagnosis.

Blastomycosis

Blastomycosis is the infection caused by the dimorphic fungus Blastomyces dermatitidis. The fungus was believed to be limited in distribution to North America but is found in Africa and northern South America, too. The exact natural habitat of B. dermatitidis is still uncertain with only rare reported isolation of the fungus from the environment. The inability to recover the organism from nature along with the absence of both a reliable skin test antigen and a sensitive serological test have significantly restricted our understanding of the epidemiology and the full clinical spectrum of blastomycosis. An accidental laboratory infection and several common source epidemics have enabled us to recognize that blastomycosis may be a self-limited pulmonary infection. Endogenous reactivation and opportunistic infections have been newly appreciated as clinical presentations of blastomycosis. This report will review blastomycosis with particular emphasis on these recent developments.

Chronic blastomycotic meningitis

Three cases of blastomycosis which presented as chronic meningitis are reported. Blastomycotic meningitis is an uncommon form of chronic fungal meningitis and is difficult to diagnose during life unless the patient has obvious systemic blastomycosis elsewhere. Evaluation of cerebrospinal fluid obtained by lumbar tap is usually not diagnostic. Obstructive hydrocephalus developed in all three patients during the course of their fungal meningitis. Culture of ventricular fluid yielded the fungus in all three patients (although only after death in one case). One patient received only minimal therapy before death whereas the third patient received a full course of amphotericin B with restoration to his premorbid state. Blastomycosis should be included in the differential diagnosis of chronic meningitis and, when suspected, the cisternal or ventricular fluid should be sampled.

Role of the conidium in dimorphism of Blastomyces dermatitidis

Fine details of yeastlike cell development of Blastomyces dermatitidis from its conidium are described and illustrated by electron micrographs. When cultured in an enriched medium at 37C, conidia of two strains of B. dermatitidis readily underwent ultrastructural changes consistent with mycelial to yeast dimorphism. Although hyphal cells contained in the conversion cultures were observed consistently to undergo profound degenerative changes, the conidia rapidly germinated to give rise to short germ tubes which subsequently enlarged to form intermediate yeast mother cells (YMC). The wall of the germ tube arose from the innermost layer of the wall of the germinant. During the transition globoid osmiophilic inclusions of unknown origin and function were observed in vacuolated areas of the germ tube and YMC cytoplasm. Yeastlike daughter cells then budded from the intermediate YMC. Since transformation was readily accomplished under in vitro conditions favoring mycelial to yeast dimorphism, it is suggested that the conidium of B. dermatitidis represents the primary infective unit of this pathogenic fungus.