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Introduction
  • Systemic mycoses consist of 4 dieases
    • Histoplasmosis (Histoplasma capsulatum)
    • Coccidiomycosis (Coccidioides immitis)
    • Blastomycosis (Blastomyces dermatitidis)
    • Paracoccidioidomycosis (Paracoccidioides brasiliensis)
  • Characteristics of systemic mycoses
    • dimorphic
      • mold in soil ("mold in the cold" - 25 deg C)
        • grown on Sabouraud's agar
      • yeast in tissue (37 deg C)
        • grown on blood agar
      • Coccidioides immitis is an exception
        • spherule (not yeast) in tissue
    • endemic to a specific area
  • Pathogenesis
    • fungi inhaled in spore
    • lungs are locally infected
    • infection disseminates hematogenously
Histoplasma capsulatum
  • Diseases
    • histoplasmosis (pneumonia)
      • hilar lymphadenopathy
      • ulcerated tongue lesions
  • Pathogenesis
    • invades macrophages 
      • oval yeast cells seen within macrophages
      • the only systemic fungus with yeast phagocytosed by macrophages
  • Transmission
    • cave exploring/spelunking  
    • endemic to Mississippi and Ohio River Valleys
      • Ohio and Tennessee
    • found in bird and bat droppings (chicken farms)
  • Laboratory
    • NOT encapsulated despite name
Coccidioides immitis
  • Diseases
    • coccidioidomycosis 
      • mild pneumonia
        • opportunistic infection in AIDS patients in Arizona
      • meningitis
      • disseminated disease to skin and bone in immunocompromised
  • Transmission
    • endemic to southwest U.S.
      • AZ, NM, southern CA, and San Joaquin Valley
    • incidence ↑ after earthquakes
      • spherules released from soil
  • Laboratory
    • spherule (not yeast) in tissue
      • spherules contain endospores seen on biopsy 
Blastomyces dermatitidis
  • Diseases
    • blastomycosis (most severe disease of the group)
      • chronic inflammatory lung disease
      • granulomatous nodules
      • dissemination to skin and bone
    • rarest of the group
  • Transmission
    • endemic to Mississippi River Valley and Central America
    • found in soil and rotting wood
  • Laboratory
    • round, broad-based budding yeast
      • thick, double refractive walls
Paracoccidioides brasiliensis 
  • Diseases
    • paracoccidioidomycosis (pneumonia) 
  • Transmission
    • endemic to Latin America
  • Laboratory
    • "captain's wheel" appearance
    • budding yeast
Presentation (Systemic mycoses)
  • 3 presentations
    • asymptomatic
      • majority of cases
      • most people never visit the doctor
    • pneumonia
      • fever
      • cough
      • may be acute or chronic
      • clinical presentation is similar to TB
    • disseminated disease
      • fever, malaise
      • meningitis, bone lytic and skin granulomas
      • seen in immunocompromised
Evaluation (Systemic mycoses)
  • Radiographs
    • CXR will show lesion
  • Biopsy
    • stained with silver stain directly or KOH prep
    • cultured on Sabouraud's or blood agar
  • Delayed hypersensitivity reaction
    • can be used to show previous exposure (similar to PPD)
      • coccidioidin
      • histoplasmin
Differential (Systemic mycoses)
  • Tuberculosis
    • similarities with TB
      • inhaled lung infection
      • wide range of severity (asymptomatic to chronic)
      • granulomas, cavitations, and calcifications
      • hematogenous dissemination
      • show previous exposure with PPD-like hypersensitivity reaction
      • however, these infections do NOT transmit from person-to-person, unlike TB
Treatment (Systemic mycoses)
  • Fluconazole or ketoconazole
    • indications
      • local infection
  • Amphotericin B
    • indications
      • systemic infection
 

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