Mycology Flashcards
what are the three types of fungi?
yeasts, molds, and dimorphic
what are some general fungi characteristics?
eukaryotic, chitin in cell walls, uni or multicellular, non-photosynthetic, obligate anaerobes, decomposers of dead material
what are the superficial mycoses?
yeasts - trichosporin, malassezia
what are the cutaneous mycoses?
molds - trichiophyton, epidermophyton, and microsporum
what is chitin?
a polysaccharide that has long chains of N-acetylglucosamine
what does the fungal membrane contain that is a good drug target?
ergosterol
what are the two ways that yeast reproduce?
budding or binary fission
what do you call networks of hyphae?
mycelium
what is the purpose of septa in hyphae?
to make compartment but not discrete cells - have pores that allow passage of material
what are spores?
something that all molds can make through mitosis or meiosis that allow dispersal of genetics and dormancy if conditions are unfavorable
what is a germ tube?
a small immture hyphae that grows from a germinating spore
what are methods to visualize fungi using microscopy?
KOH, calcoflour white, india ink, methenamine silver
what is sabouraud’s agar?
inhibits bacterial growth, but promotes fungal growth
what are three classes of antifungal treatments?
azoles, polyenes, echinocandins
what do azoles do?
they inhibit synthesis of ergosterol
what do polyenes do?
one example is amphotericin
they bind to ergosterol and make pores, causing osmotic death
what do echinocandins do?
they block cell wall synthesis by inhibiting the synthesis of beta-glucan
what are some examples of azoles?
fluconazole, voriconazole, itraconazole
what are some side effects of azoles?
heptotoxicity is rare, voriconazole can lead to visual disturbances or hepatitis
what are some examples of polyenes?
liposomal amphotericin B, nystatin (topical)
what are some side effects of polyenes?
renal toxicity, chills, headache
what are side effects of echinocandins?
GI effects, flushing
what are some endothelial defenses to fungi?
dectin-1 - a PAMP that recognizes beta-glucan
defensins
what do neutrophils protect against?
molds
what do Th1 cells protect against?
intracellular fungi
what do Th17 cells protect against?
mucosal fungal infections
what are characteristics of superficial mycoses?
colonized keratinized outer layer of hair, skin, nails; noninflammatory; easy to treat
what are characteristics of cutaneous mycoses?
invade/colonize in epidermis and cause inflammatory response
what is the major superficial mycosis?
pityriasis versicolor (aka tinea versicolor)
what are the two species that cause pityriasis versicolor?
malassezia furfur and globosa
what diagnostic tool can be used for pirtyriasis versicolor?
wood’s lamp - appears yellow-green
what is does pityriasis versicolor look like microscopically?
yeast-like cells and pseudohyphae
what is the treatment for pityriasis versicolor?
topical or oral azoles, selenium sulfide shampoo
how do you identify cutaneous mycoses based on microscopy?
the presence of macro and microconidia
what are some examples of cutaneous mycoses?
tinea, athlete’s foot, ringworm
what a mycosis that affects your nails?
tinia unguium aka onchomycosis
how do you treat skin cutaneous mycoses?
topical azoles and terbinafine
how do you treat hair and nail cutaneous mycoses?
oral azoles, terbinafine, and griseofulvin (hepatotoxicity)
what is sporotrichosis?
a subcutaneous mycosis that is caused by a dimorphic fungus that lives in soil and vegetation
what is a special microscopic determinant of sporotrichosis?
splendore-hoeppli phenomenon in which you see a pink granulomatous center surrounded by a starburst
what is the treatment for sporotrichosis?
itraconazole, KI
how does sporotrichosis spread?
along the lymphatics, leaving lesions as it travels
what is chromomycosis?
a subcutaneous fungal infection that manifests with warty/nodular lesions that is more common in the tropics
what are some microscopic characteristics of chromomycosis?
muriform cells - brown with septation (aka Medlar bodies); often present with granulomatous inflammation
how do you treat chromomycosis?
itraconazole, terbinafine, local heat, cryotherapy, surgery contraindicated
what is eumycotic mycetoma?
a deep, serious subcutaneous infection manifesting by localized swelling and discharege from sinuses containing black granules
what are some possible fungi that cause eumycotic mycetomas?
madurella, fusarium, acremonium, exophiala, scedosporium
what is treatment for eumycotic mycetomas?
antifungals, surgery maybe - oftentimes amputation is bad enough
