Fungi Flashcards
General description fungi
Aerobic, eukaryotic cells
Unicellular growth form of fungi
Yeast
Threadlike branching, cylindrical tubules composed of fungal cells attached end to end
Hyphae
Multicellular colonies composed of clumps of intertwined, branching hyphae
Mold
Reproduction bodies of molds
Spores
Fungi that can grow either as yeast or mold, depending on environmental conditions and temperature
Dimorphic fungi
What do dimorphic fungi typically grow as at body temperature?
Yeast
Fungi that live in and utilize organic matter as an energy source
Saprophyte
Describe fungal morphology
Bilayer cell membrane with sterols
Cell wall
Capsule (avoid Phagocytosis)
Sterol in fungi that infect humans
Ergosterol
Stain for cryptococcus neoformans
India ink, shows capsule
Fungal infections of skin, hair, and nail
Dermatophytosis
What is the genius is the genius for common fungal hair/ skin/ nail infections
Tinea
Fungal infection that causes thrush, diaper rash, and vaginitis
Candida albicans
What disease does sporthix schenkii cause?
Sporotrichosis
Transmission of Sporotrichosis
Fungus enters skin from puncture of a thorn (fungus grows on plants)
Fungal disease from fungus that grows on rotting wood
Chroniblastomycosis
Regionally important fungi that cause systemic disease
Histoplasma capsulatum
Blastomyces dermatitidis
Coccidioides immitis
Morphology of blasto, histo, and coccidioides
Dimorphic
Yeast at body temp on blood sugar
Mycelial with spores under 25C
Geography of histoplasma
Mississippi river basin
Geography of blastomycosis
Mississippi river basin
Geography coccidioides
Southwest and northern Meixco
Most common opportunistic infection in AIDS patients that reside in AZ
Coccidioides
Transmission of histo, blasto, and coccidioides
Inhaled spore
Histo- bird and bat droppings
Blasto- soil and rotten wood
Coccidioides - soil
Clinical manifestations of histo, blasto, and coccidioides
1) asymptomatic (most)
2) pneumonia
3) disseminated (rare, immunocompromised)
Best method to dx histo, blasto, coccidioides? What method is not very useful?
Tissue biopsy
Skin PPD not useful since most people exposed and asymptomatic
Like TB, what can the pneumo look like in histo, blasto, and coccidioides?
Lung calcifications, granulomas, and cavitations
Morphology of cryptococcus
Encapsulated yeast
Two species of cryptococcus that cause disease
Neoformans and gattii
Transmission of cryptococcus neoformans
Inhalation, usually from pigeon dropings
Cryptococcus clinical in severely immunocompromised hosts
-meningitis, which leads to death without treatment
Clinical signs candida in immunocompromised hosts
1) esophagitis (spread of thrush)
2) disseminated- any organ
Dx disseminated candidas
Candida detected in blood
3 clinical manifestations of aspergillus
1) allergic bronchopulmonary aspergillosis (ABPA)
2) aspergilloma
3) invasive aspergillosis
Form of aspergillosis when spores inhaled and there is an IgE hypersensitivity reaction with an increase in eosinophils (similar to asthma)
Allergic bronchopulmonary aspergillosis
Describe aspergilloma
In TB patients, balls of fungal aspergillus form in lung cavities
Who is impacted by invasive aspergillosis?
End-stage AIDS, high dose steroids for graft
What fungi produces the mycotoxin aflatoxin
Aspergillus
Toxins that cause liver damage
Mycotoxins
Reservoir for aspergillus
Air
Opportunistic fungal infection that aggressively invades sinuses, cranial bones, and blood vessels and requires aggressive treatment
Mucormycosis
Who is at risk for mucormycosis?
Diabetics
Immunocompromised
Burn victims
Persons taking iron chelator deferoxamind
Where is mucormycosis found?
Everywhere in the environment
Bacteria that grow like fungi in soil and water
Acinomycetes and norcardia
Basic description of actinomycete
Gram positive rod
Anaerobic
Filamentous
Part of normal mouth and GI flora
Clinical manifestation acinomycete
- causes abscesses in GI tract or mouth when there is trauma to the mucous mebrane
Key differences between norcardia and actinomyces
- norcardia- acid fast
- actinomyces- sulfur granules
Basic description norcardia
Weakly gram positive
Partially acid fast
Gram positive rod
Branching filaments
Clinical manifestations of norcardia
Looks like TB
Inhaled
Cavitations of lung
Erosion pleural space
Who is at risk for norcardia
- immunocompromised, esp those taking steroids
Is norcardia part of the normal GI flora?
No, never
What do antifungal drugs target?
Ergosterol in fungal cells wall
What are the types of antifungals
1) amphotericin b
2) flucytosine (anti metabolic)
3) azoles
4) glycan synthesis inhibitors (aka echinocandins
5) allylamines (topical)
First line antifungal for serious systemic infections, works against most fungus. iV, Many side effects.
Amphotericin B
Common side effects of amphotericin B
Renal toxicity
Acute febrile reaction
Anemia
Inflammation of vein
How to reduce nephrotoxicity from amphotericin B
Add lipids
Anti-fungals used in conjunction with amphotericin B (due to resistance). Used solely for cryptococcus meningitis
Flucytosine
Common side effect of anti- metabolite drugs (flucytosine, methotrexate, sulfa-drugs, 5- fluorouracil, etc.)
- Leukopenia and thrombocytopenia resulting from bone marrow depression
- nausea, vomiting, diarrhea
Hat are the two families of azole antifungals?
-imidazoles
- triazoles
Drugs that are active against broad spectrum fungi by inhibiting cytochrome P-450
Azoles
Difference between imidazoles and triazoles
Triazoles tolerated orally and used for systemic fungal infections
Imidazoles mainly topical or suppository for local fungal infection, otherwise toxic
Toxicity keta onazole
1) gi
2) hepatotoxicity
3) inhibits testosterone synthesis
4) adrenal suppression
Primary antifungal used for susceptible candida infections (superficial and disseminated)
Fluconazole (one of the triazoles)
Antifungal used to trade chromoblastomycosis, coccidioidomycosis, blastomycosis, sporotrichosis, and indolent aspergillus
Itraconazole
Main antifungal against invasive aspergillus and fluconazole resistant candida spp. Board spectrum, not as toxic as amphotericin B
Voriconazole
Newest azoles that are used for bad cases of aspergillus and mucormycosis which are otherwise hard to treat
Posaconazole and isavuconazole
iV antifungals that treat species of candida and invasive aspergillosis that fails conventional therapy
Echinicandins
Used for oral, esophageal, and gastric candidas (formula oral, swish and spit out or topical for vaginal candida) . Too toxic for IV)
Nystatin
Static antifungal that inhibits fungal growth in skin, hair, and nails
Griseofulvin
Treatment for sporotrichosis
Potassium iodide
