Molds and Yeast (Boyington) Flashcards
contrast mold vs. yeast structure
mold: multicellular, filamentous fungus made up of tubular structures. yeast: unicellular, smooth + round/ovoid cells larger than bacteria
contrast mold vs. yeast growth + reproduction
mold: reproduce by conidia = asexual spores, than when airborne = transmission, allergy and infection. grow by branching, extension at hyphal tip. yeast: reproduce by asexual budding. grow within phagocytes
contrast mold vs. yeast infection source in humans
mold: enviornmental. yeast: endogenous flora
contrast mold vs. yeast colony appearance
mold: fuzzy. yeast: smooth and flat colonies
dimorphic fungi: definition
fungus that can grow either as a yeast or mold
dimorphic fungi: when is it yeast? mold?
yeast at body temperature in host. mold in lab/room temperature
5 medically important dimorphic fungi
Blastomycosis, Coccidioidomycosis, Paracoccidioidomycosis, Histoplasmosis, Sporotrichosis
fungal cell wall: 3 main parts
chitin = polymers extruded by plasma membrane. glucans = polymers that cross link chitin. mannoproteins = structural proteins.
fungal cell membrane: what is different about it from human cells
phospholipid bilayer with ergosterol, a human cholesterol equivalent. can be an antifungal target
4 classes of fungal diseases
superficial/cuteaneous aka dermatophytosis. subcutaneous aka candida. opportunistic/invasive. endemic.
risk factors for invasive fungal infections
immunosuppression, neutropenia. promotion of fungal colonization with antibiotic use. providing access to blood/organs with catheters like via IV, central line, organ transplant.
5 methods to diagnose fungal infections in the lab
direct microscopy. culture. serology. antigen detection. nucleic acid testing
aspergillus: highest rates of infection in who?
in those with heavy/lengthy immunosuppression, or with relapse of malignancy. also in those with hematopoietic stem cell or solid organ transplants
aspergillus: three clinical syndromes
allergic (ABPA = allergic bronchopulmonary aspergillosis), colonization, invasive (IPA = invasive pulmonary aspergillosis)
ABPA, asllergic bronchopulmonary aspergillosis: what? get what? see in who?
long term allergic response to aspergillus: get impacted mucus in bronchi, eosinophilic pneumonia, seen in patients with persistent asthma and CF
aspergillus: colonization - see what? treatment?
fungus ball (mass of hyphae) growing in previously existing lung cavity, usually asymptomatic can be treated w/ surgery
invasive pulmonary aspergillus: risk factor? symptoms?
prolonged neutropenia, then inhale conidia. dry cough that worsens, pleuritic chest pain, fever, hemoptysis, shortness of breath
IPA: what do you see when imaging?
dense, nodular lung infiltrates. CT “halo” and cavitation, crescent sign.
how to diagnose invasive aspergillus
tissue biopsy. culture. radiography. galactomanna detection using enzyme immunosassays
treatment of invasive aspergillus
voriconazole. alternatives: echinocandins, posaconazole, itraconazole
