Molds and Yeast (Boyington)

Question 1

contrast mold vs. yeast structure

Answer 1

mold: multicellular, filamentous fungus made up of tubular structures. yeast: unicellular, smooth + round/ovoid cells larger than bacteria

Question 2

contrast mold vs. yeast growth + reproduction

Answer 2

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

Question 3

contrast mold vs. yeast infection source in humans

Answer 3

mold: enviornmental. yeast: endogenous flora

Question 4

contrast mold vs. yeast colony appearance

Answer 4

mold: fuzzy. yeast: smooth and flat colonies

Question 5

dimorphic fungi: definition

Answer 5

fungus that can grow either as a yeast or mold

Question 6

dimorphic fungi: when is it yeast? mold?

Answer 6

yeast at body temperature in host. mold in lab/room temperature

Question 7

5 medically important dimorphic fungi

Answer 7

Blastomycosis, Coccidioidomycosis, Paracoccidioidomycosis, Histoplasmosis, Sporotrichosis

Question 8

fungal cell wall: 3 main parts

Answer 8

chitin = polymers extruded by plasma membrane. glucans = polymers that cross link chitin. mannoproteins = structural proteins.

Question 9

fungal cell membrane: what is different about it from human cells

Answer 9

phospholipid bilayer with ergosterol, a human cholesterol equivalent. can be an antifungal target

Question 10

4 classes of fungal diseases

Answer 10

superficial/cuteaneous aka dermatophytosis. subcutaneous aka candida. opportunistic/invasive. endemic.

Question 11

risk factors for invasive fungal infections

Answer 11

immunosuppression, neutropenia. promotion of fungal colonization with antibiotic use. providing access to blood/organs with catheters like via IV, central line, organ transplant.

Question 12

5 methods to diagnose fungal infections in the lab

Answer 12

direct microscopy. culture. serology. antigen detection. nucleic acid testing

Question 13

aspergillus: highest rates of infection in who?

Answer 13

in those with heavy/lengthy immunosuppression, or with relapse of malignancy. also in those with hematopoietic stem cell or solid organ transplants

Question 14

aspergillus: three clinical syndromes

Answer 14

allergic (ABPA = allergic bronchopulmonary aspergillosis), colonization, invasive (IPA = invasive pulmonary aspergillosis)

Question 15

ABPA, asllergic bronchopulmonary aspergillosis: what? get what? see in who?

Answer 15

long term allergic response to aspergillus: get impacted mucus in bronchi, eosinophilic pneumonia, seen in patients with persistent asthma and CF

Question 16

aspergillus: colonization - see what? treatment?

Answer 16

fungus ball (mass of hyphae) growing in previously existing lung cavity, usually asymptomatic can be treated w/ surgery

Question 17

invasive pulmonary aspergillus: risk factor? symptoms?

Answer 17

prolonged neutropenia, then inhale conidia. dry cough that worsens, pleuritic chest pain, fever, hemoptysis, shortness of breath

Question 18

IPA: what do you see when imaging?

Answer 18

dense, nodular lung infiltrates. CT “halo” and cavitation, crescent sign.

Question 19

how to diagnose invasive aspergillus

Answer 19

tissue biopsy. culture. radiography. galactomanna detection using enzyme immunosassays

Question 20

treatment of invasive aspergillus

Answer 20

voriconazole. alternatives: echinocandins, posaconazole, itraconazole