Microbiology
Summary
Blastomyces dermatitidis is a dimorphic fungus that causes blastomycosis. B. dermatitidis is primarily found in eastern and central United States near the Ohio and Mississippi River valleys and the Great Lakes region. It reproduces by budding, with the daughter cells being attached to the parent cell via a broad base. This fungus is transmitted via inhalation of mold spores. Once inhaled, the fungus takes yeast form and begin colonizing the lungs.
After inhalation, infection can cause patchy alveolar infiltrates or 'haziness' in the lungs on chest X-rays. Blastomyces can also lead to systemic infections that can spread to other organs like the skin and bones, especially in immunocompromised individuals. Diagnosis can be achieved either through microscopic examination, culture, or a urine antigen test. The choice of treatment is typically itraconazole for local infections or amphotericin B for severe systemic infections.
Lesson Outline
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FAQs
Blastomyces dermatitidis is a dimorphic fungus, which means it can exist in two forms, yeast and mold, depending on its environment. It's the agent responsible for blastomycosis, a fungal infection that primarily affects the lungs but can spread to other parts of the body as well.
Blastomyces dermatitidis is predominantly found in the environment, particularly in moist soil and decaying organic matter. It's geographically associated with the Ohio river valley and the Great Lakes region in North America, but is also found in other parts of the world.
Infection is usually acquired by inhaling aerosolized spores of the fungus from the environment. The fungus can cause a local lung infection with symptoms including cough, fever, and fatigue. In severe cases or in immunocompromised individuals, the infection can become systemic and affect other parts of the body.
Under the microscope, Blastomyces dermatitidis is recognized by its broad-based budding of yeast cells. Its morphology is a key identifier in laboratory testing.
Blastomycosis can be diagnosed through a urine antigen test, cultures, or biopsies typically from the lungs or skin. As for treatment, antifungal medication like itraconazole is commonly used for less severe cases and amphotericin B is utilized for more severe or systemic infections.
