questions 5

Fungi

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Topic updated on 03/13/15 10:45pm

Microbiology Overview
 
Fungi Table
 
Cutaneous and subcutaneous mycoses
  Disease Treatment
Malassezia furfur Tinea versicolor Miconazole
Selenium sulfide
Trichophyton, Microsporum, Epidermophyton Tineas (ringworm, jock itch, and athlete's foot) Imidazoles
Sporothrix schenckii Sporotrichosis (rose gardner's disease) Itraconazole
Systemic mycoses
Histoplasma capsulatum Histoplasmosis (pneumonia) Fluconazole
Amphotericin B
Coccidioides immitis Coccidioidomycosis (pneumonia, meningitis, skin/bone infection)  Fluconazole
Amphotericin B
Blastomyces dermatitidis Blastomycosis (chronic inflammatory lung disease, skin/bone infection) Fluconazole
Amphotericin B
Paracoccidioides brasiliensis Paracoccidioidomycosis (pneumonia) Fluconazole
Amphotericin B
Opportunistic mycoses
Candida albicans Oral thrush
Candida intertrigo
Vaginitis
Disseminated disease in immunocompromised (neutropenia)  
Nystatin
Amphotericin B
Cryptococcus neoformans Cryptococcosis (meningitis, pneumonia, skin/bone infections) Amphotericin B +
Flucytosine
Aspergillus Allergic bronchopulmonary aspergillosis
Aspergilloma
Invasive aspergillosis
Itraconazole
Amphotericin B
Mucor, Rhizopus Mucormycosis (rhinocerebral infection) Amphotericin B
Pneumocystis jiroveci PCP (diffuse interstitial pneumonia) TMP-SMX
 
Fungi Introduction
  • Fungi is a large group of eukaryotic organisms including yeasts, molds, and mushrooms
  • Yeast
    • unicellular fungi
    • reproduce by budding
      • reproduce more slowly than bacteria
    • cells are spherical to ellipsoidal in shape
    • buds that do not separate form long chains of yeast cells called pseudohyphae
      • Candida albicans forms pseudohyphae
  • Molds
    • multicellular colonies
      • composed of clumps of intertwined branching hyphae
    • grow by longitudinal extension
    • produce spores
  • Dimorphic fungi
    • can grow as either yeast or mold depending on the environmental conditions
      • usually grows as a yeast at body temperatures
      • "mold in the cold"
    • examples
      • Histoplasma
      • Blastomyces
      • Coccidioides
      • Sporothrix
Fungal Morphology
  • Spores
    • the reproductive structure of molds
      • adapted for dispersal
    • conidia are asexual fungal spores (Greek: "konia" = "dust")
      • most fungal spores are asexual
      • types of conidia include blastoconidia and arthroconidia
      • coccidioidomycosis and histoplasmosis are transmitted by inhalation of asexual species
  • Hyphae
    • long, threadlike, branching, filamentous, tubular structure of a fungus
    • composed of fungal cells attached end to end
    • grow by extending from the ends of the tubules
  • Cell membrane
    • innermost layer around fungal cytoplasm
    • contains ergosterol
      • analogous to cholesterol in humans
      • amphotericin B and nystatin bind to ergosterol
      • ketoconazole inhibits ergosterol synthesis
  • Cell wall
    • surrounds cell membrane
    • contains mostly complex carbohydrates
      • explains calcification in chronic infection
    • fungal cell walls are potent antigens
  • Capsule
    • polysaccharide coating surrounding the cell wall
    • visualized with India ink stain
    • can be an antiphagocytic virulence factor
      • used by Cryptococcus neoformans


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(M1.MC.75) A 34-year-old male from Southern California presents to his primary care physician with a complaint of cough, fever, night sweats, and general malaise. He also reports that he recently developed a rash that is very concerning. He states that he has had these symptoms for a few days and they have failed to resolve. Upon questioning, the patient complains of having to work outside recently to complete repairs on his house, which was damaged in a recent earthquake. The physician states that he believes the patient to have a fungal pneumonia. Which of the following histologic images best represents this patient's infection? Topic Review Topic
FIGURES: A   B   C   D   E  

1. Figure A
2. Figure B
3. Figure C
4. Figure D
5. Figure E

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