fungi Flashcards
What are the anti-fungal agents that act on the cell wall? What is their mechanism of action?
echinocandins - inhibit glucan synthesis
What are the anti-fungal agents that act on the cell membrane?
direct damage to cell membrane through pore formation - polyenes (amphotercin B, nystatin)
inhibitors of ergosterol synthesis - azoles
what are the anti-fungal agents that act in the nucleus?
flucytosine - inhibits nucleic acid synthesis
griseofluvin - inhibits microtubules/mitosis
What are the topical antifungals?
nystatin, clotrimazole, miconazole
What anti-fungal agent should you use for fungal nail infections (onychomycosis)?
terbinafine
what are the names of the azole drugs?
ketoconazole, fluconazole, itraconazole, voriconazole, posaconazole
What are the drugs in the echinocandin family?
caspofungin
What are the toxicities related to caspofungin? Amphotericin B?
Caspofungin - infusion related flushing, fever, rash. GI upset. IV site irritation
Amphotericin B - infusion related flushing, fever, rash. Nephrotoxicity with wasting of K+ and Mg2+
What are the toxicites related to the azole drugs?
All azoles - elevated LFTs and drug interactions because they interact with cytochrome P450 enzymes
fluconazole - N/V, rash
itraconazole - taste disturbances, osmotic diarrhea, CHF, N/V
voriconazole - visual disturbances
posaconazole - elevated LFTs
what are the toxicities related to flucytosine?
bone marrow toxicity, elevated LFTs
What are the opportunistic fungi?
candida, cryptococcus neoformans, aspergillus, pneumocystis jiroveci, zygomycetes
What are the systemic, endemic dimorphic fungi?
histoplasma capsulatum, blastomycetes dermatitidis, coccidiodes immitis, paracoccidoides brasilensis, penicillium marneffei
what are the superficial dermatophytes? subcutaneous mycoses?
trichophyton, malessezia
sporothrix, madurella
What are the 3 main clinical manifestations of candida albicans?
cutaneous - diaper rash, skin infections in intertriginous areas, nail plate
mucosal - oral thrush, esopgagitis, vulvovaginal
systemic/disseminated
What are the main clinical manifestations of cryptococcus neoformans?
asymptomatic, meningitis, pneumonia, skin lesions [cryptic MAPS]
How do you diagnose cryptococcus neoformans?
capsular antigen test, latex agglutination test, India ink stain, culture and stain with PAS and silver stain
How do you treat cryptococcal meningitis? Pulmonary cryptococcus?
meningitis - amphotericin B +/- flucytosine, maintenance with fluconazole
pulmonary cryptococcus - fluconazole
How does crytococcus avoid the immune system/virulence factors?
capsule, phenotypic switching of capsular antigens, melanin (antioxidant, inhibits antibody-mediated phagocytosis)
What are the four clinical manifestations of aspergillus?
aspergilloma - fungal ball in preformed cavities in the lung (TB, emphysema, COPD)
allergic bronchopulmonary aspergillosis - asthma or CF
disseminated aspergillosis
cutaneous aspergillosis
which species of fungus produces aflatoxin? What disease is consumption of aflatoxin associated with?
aspergillus flavus
liver damage and hepatocellular carcinoma
what is the treatment for aspergillus?
voriconazole, amphotericin B
which fungus is associated with a fruiting head on lactophenol blue stain?
aspergillus
what fungus is associated with wide, nonseptate, right-angle hyphae? with thin, septate, acute-angle hyphae?
right angle - zygomycetes
acute angle - aspergillus
What are the two clinical manifestations of pneumocystis jiroveci?
pneumonia - “ground glass” appearance on CXR
pneumothorax
what is the drug of choice for treatment of pneumocystis?
TMP-SMX (bactrim)
used for prophylaxis too
What are the clinical manifestations of zygomycetes?
black, necrotic cutaneous lesions
What are the risk factors for zygomycetes?
diabetic ketoacidosis, desferoxamine therapy, neutropenia, bone marrow transplant [diabetic dog named Zygo nawing a bone]
How do you treat a zygomycetes infection?
aggressive surgical debridement
amphotericin B
posaconazole has activity
what is the only fungus with a capsule?
cryptococcus
NOT histoplasma capsulatum
what fungi is found in pigeon droppings? bat and bird droppings?
cryptococcus
histoplasma
Which dimorphic fungi has a mold and spherule form, instead of a normal mold and yeast form?
coccidioides
Which fungi is characterized by the mariner’s wheel upon visualization by microscopy?
paracoccidioides
Which fungi is very common in AIDS patients in northern Thailand?
penicillium marneffei
What organ do the systemic endemic dimorphic fungi usually manifest in?
The lungs. Usually cause some sort of pulmonary disease
Which fungi has broad based budding?
blastomycetes dermatiditis
What diseases does trichophyton cause?
athlete’s foot, jock itch, onychomycosis, ringworm
what diseases does malassezia fur fur cause?
pytiriasis versicolor - hyper- or hypopigmented patches on the skin usually acquired on the beach
What are the clinical manifestations of sporothrix schenckii? How is it commonly acquired?
Subcutaneous nodules that spread along the lymphatic tracts of the arm. Often acquired from the prick of a rose thorn.
What are the clinical manifestations of a Madurella infection? How would you treat this kind of infection?
slow progressing ulcerative lesions on the foot (found in soil) with black fungal granules in discharge. Treat with surgical debridement or amputation - doesn’t respond well to anti fungal therapy
What are the organisms that can cause a fungal pneumonia?
aspergillus, cryptococcus, blastomycetes, histoplasma, coccidioides, paracoccidioides, pneumocystis jiroveci
