Updated: 12/31/2021

Systemic Mycoses

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  • Snapshot
    • A 38-year-old man presents to an urgent care clinic in Ohio for a 3-week cough. He reports having fevers, chills, and fatigue. He recently went on a local hiking trip that included waterfalls, freshwater lakes, and caves. He reports his cough was worse in the beginning but has lingered. He denies any rashes, vomiting, or diarrhea. A chest radiograph shows patchy pulmonary infiltrates and hilar lymphadenopathy. A sputum sample under microscopy shows macrophages with intracellular yeast cells. (Histoplasmosis)
  • Introduction
    • Introduction
      • dimorphic yeasts
        • mold form in the soil, outside the body
          • grows on Sabouraud agar
        • yeast form in tissues, inside the body
          • grows on blood agar
        • Coccidioides immitis is an exception
          • spherule form, not yeast, in tissue
      • clinical syndromes
        • pneumonia
        • chronic inflammatory lung disease
        • systemic dissemination
      • Overview of Systemic Mycoses
      • Clinical Syndrome
      • Histoplasmosis
      • Coccidioidomycosis
      • Blastomycosis
      • Paracoccidioidomycosis
      • Organism
      • Histoplasma capsulatum
      • Coccidioides immitis
      • Coccidioides posadasii
      •   Blastomyces dermatitidis
      • Paracoccidioides brasiliensis
      • Paracoccidioides lutzii
      • Demographics
      • Mississippi
      • Ohio River Valley
      • Southwestern US
      • California
      •  
      • Eastern US
      • Central US
      • Latin America
      • Skin manifestations
      • Ulcers on oral mucosa
      • Erythema nodosum
      • Erythema multiforme
      •   Verrucous skin lesions
      • Verrucous skin lesions
      • Histology
      • Macrophages filled with fungus cells
      • Spherules (larger than red blood cells (RBCs)) filled with endospores
      •   Broad-based budding yeast (same size as RBCs)
      • Budding yeast larger than RBCs
    • Differential
      • tuberculosis
        • also affects the pulmonary system
        • causes granulomas, cavitations, and calcifications
        • unlike these systemic mycoses, tuberculosis can be transmitted person to person
    • Treatment
      • amphotericin B
        • systemic infections
      • itraconazole or fluconazole
        • localized infections
  • EPIDEMIOLOGY
    • demographics
      • depends on geographic location
    • transmission
      • inhalation of spores
      • cannot be transmitted between people
  • ETIOLOGY
    • pathogenesis
      • inhalation causes a pulmonary infection
      • fungi can then disseminate to other organs, particularly the skin
      • causes granulomas
        • composed of epithelioid cells and multinucleated giant cells
        • Th1 mediated
  • Histoplasmosis
    • Histoplasma capsulatum
      • demographics
        • Mississippi
        • Ohio River Valley (Ohio and Tennessee)
      • risk factors
        • bird or bat excretions
        • chicken farms
        • exploring caves or spelunking
        • HIV infection
    • Presentation
      • pneumonia
        • usually self-limiting
      • chronic cavitary lung disease
      • hilar lymphadenopathy
      • gastrointestinal symptoms
      • splenomegaly
      • oral mucosal ulcers on tongue or palate
    • Imaging
      • chest radiograph
        • normal or with patchy infiltrates with hilar/mediastinal lymphadenopathy
    • Studies
      • detection of antigen in serum or urine
      • tissue biopsy
        • methenamine silver or periodic acid-Schiff stains show oval yeasts within macrophages
  • Coccidioidomycosis
    • Coccidioides immitis or Coccidioides posadasii
      • demographics
        • southwestern US
          • Arizona, New Mexico, and southern California
        • Central and South America
      • risk factors
        • earthquakes releases spherules from soil
    • Presentation
      • pneumonia
      • dissemination to skin in 50% of patients
        • erythema nodosum
          • “desert bumps”
        • erythema multiforme
      • arthralgias
        • “desert rheumatism”
      • meningitis
    • Imaging
      • chest radiograph
        • consolidations, hilar/mediastinal lymphadenopathy, or pleural effusions
      • chest computed tomography (CT)
        • multifocal ground glass opacities
    • Studies
      • detection of immunoglobulin M (IgM) in serum
      • detection of antigen in serum
      • tissue biopsy
        • spherules (larger than RBCs) filled with endospores
  • Blastomycosis
    • Blastomyces dermatitidis
      • demographics
        • eastern US
        • central US
      • risk factors
        • HIV infection
    • Presentation
      • majority are asymptomatic
      • pneumonia
      • severe chronic inflammatory lung disease
      • dissemination to skin, often on the face
        • verrucous skin lesions
        • granulomatous nodules
        • ulcers
    • Imaging
      • chest CT
        • infiltrates without hilar lymphadenopathy
        • cavitary lesions in chronic disease
    • Studies
      • tissue biopsy
        • fungal stain shows broad-based budding yeast
        • same size as red blood cells (RBCs)
  • Paracoccidioidomycosis
    • Paracoccidioides brasiliensis or Paracoccidioides lutzii
      • also known as “South American blastomycosis”
      • demographics
        • Latin America
        • male > female
      • risk factors
        • contact with soil
    • Presentation
      • severe chronic inflammatory lung disease
      • pneumonia
      • lymphadenopathy
      • dissemination to skin, often on the face but can also affect mucous membranes
        • verrucous skin lesions
        • granulomatous nodules
    • Imaging
      • chest radiograph
        • bilateral iniltrates without cavitation
    • Studies
      • tissue biopsy
        • budding yeast
        • "captain’s wheel” formation
        • granulomas
    • Sporothrix schenckii
      • typically a localized infection but can present systemically
        • localized disease can present with painful nodules traveling along lymphatic channels
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