Fungal Infections Flashcards
What is fungal cell membrane made of?
Ergosterol
What are the two morphological forms of fungi?
Unicellular - yeasts; Multicellular filamentous - mold
What are the two forms in which fungi are found?
Normal human flora - yeasts; Environment - Molds
What is the primary mechanisms for containing fungal infections?
Neutrophil phagocytosis
What is mycoses/.
Fungal infection
What are the two types of mycoses?
- Endemic infection - caused by geographically confined true pathogens;
- Opportunistic infection - caused by fungi that are not true pathogens
What is acute disseminated histoplasmosis?
Usually occurs in immunocompromised patients
What is chronic disseminated histoplasmosis?
Observed in older adults with no obvious immune deficiency
What are the symptoms of Blastomyces?
causes pneumonia. Skin lesions develop as a result of hematogenous dissemination
What important structures do Coccidiodes form?
Spherules that contain hundreds of endospores. (Dimorphism is NOT temperature dependent)
What is the most frequent opportunistic fungal pathogen?
Candida albicans
What is Thrush?
Thick, white lesions of the oropharyngeal and vaginal mucosa
What is intertriginous candidiasis?
Proliferation in warm, moist areas of skin (diaper rash)
What does cryptococcus neoformans form?
A CAPSULE in tissues, but not in the environment. Results in meningitis.
What does candida end up affecting?
The liver
What does melanin do?
Increases strength of cell wall increasing resistance to enzyme degradation and free radicals
What are the two types of Major pathogenic species of Aspergillus and what is special about them?
A. fumigatus and A. flavus. They DO NOT GROUW IN NORMAL TISSUE (must invade profoundly immunocompromised patients)
What is “angioinvasive”
Hyphae invade through blood vessel walls causing tissue infarction, hemorrhage, and necrosis.
Mucormycoses are similar to Aspergillus in what respect?
Both are angioinvasive
What are the two forms of Mucormycoses?
Rhinocerebral form - unique to diabetics; Disseminated zygomycosis - lesions of pulmonary system
What is special about pneumocystis?
- Has never been grown in vitro.
2. Was the sentinel infection in AIDS, malnourished children, and immunocompromised individuals
What is the most common fungal infection in humans?
Dermatophyte
What is the most common pathogenic fungal infection in humans?
Candidia
What are the three etiological genera associated with dermatophyte skin infections?
Microsporum, trichophyton, epidermophyton
How do dermatophytes enter the skin?
Must have some sort of skin trauma (continuous moist conditions)
What type of Mycoses result in infections caused by fungal pathogens that are geographically restricted?
Endemic Mycoses
What type of Mycoses causes systemic infections only in immunocompromised patients?
Opportunistic mycoses
What type of mycoses result in infections caused by fungi that are not true pathogens?
Opportunistic mycoses
What type of mycoses are considered “true pathogens” that typically result in systemic infections in healthy individuals?
Endemic infections
Describe how Polyenes (amphotericin B) are effective in treating coccidodiomycosis
Polyenes bind to the cell wall ergosterol of the coccidodio- and form channels
Describe why Azoles (itraconazole) is effective in treating coccidiodiomycosis
Azoles interfere with the ergosterol synthesis in the coccidodio-
What is the most frequent opportunistic fungal pathogen?
Candida albicans
How/when does Candida albicans cause disease in humans?
Usually endogenous to humans, therefore only causes disease if the normal flora is disrupted
What is different about infection by candida albicans (what kind of exception is it?)
Dimorphism exception - Mycelial form (not yeast form) causes disease in humans.
Where is cryptococcus neoformans found?
It is yeast found in soil (best at 37 degrees) that is contaminated with bird (pigeon) excreta
Describe what is important about the capsule associated with cryptococcus neoformans
Large polysaccharide capsule that is in the tissue, but not in the environment (only makes when needed due to body temp)
What fungal outbreak is commonly associate with construction, demolition, or renovation activities in or near hospital wards accomodating immunocompromised patients?
Nosocomial outbreaks of invasive aspergillosis
What 3 conditions are required for growth of fungal infections on humans?
- Trauma
- Wetness
- Warmth
