Fungi

Question 1

Fungal versus mammalian plasma membrane sterols

Answer 1

Ergosterol (important target for antifungal therapy) versus cholesterol

Question 2

Fungal cell wall composition

Answer 2

Glucan and chitin

Question 3

Fungal virulence factors

Answer 3

Cell wall, exoenzymes/toxins

Question 4

Fungi: Dimorphism two growth forms

Answer 4

Molds or yeasts

Question 5

How do molds grow

Answer 5

Hyphae (Microscopic, branching, thread-like filaments) -> Mycelium

Question 6

Hyphae two types

Answer 6

Septate (divided by cross walls)

Nonseptate and multinucleate

Question 7

Yeast description

Answer 7

Single, ovoid, or spherical cells with a rigid cell wall

Question 8

Candida morphogenesis

Answer 8

Present as yeast form but can elongate as hypha like structure (germ-tube)

Question 9

Fungal virulence factors

Answer 9

Thermotolerance, cell wall components, exoenzymes, toxins

Question 10

Host risk factors for fungal infection

Answer 10

Immunosuppression (neutropenia, cell-mediated immune dysfunction), previous antibiotic use, warm/wet environment, malnutrition, extremes of age, indwelling catheters/hardware

Question 11

Fungal disease pathogenesis

Answer 11

Adherence, invasion, local tissue destruction, immunogenic cell wall (e.g. hypersensitivity to cell wall components)

Question 12

What are the endemic fungi (with location)? Detection?

Answer 12

Histoplasma - Ohio-Mississippi River Valley
Blastomyces - North Central U.S.
Coccidioides - Southern U.S. and Latin America

Antigen detection helpful
Coccidioides still use serology (but generally not very useful)

Question 13

What cause mild cutaneous fungal infections?

Answer 13

Trichophyton, Epidermophyton, Microsporum

Question 14

What is KOH used for?

Answer 14

Body fluids, cervical/vaginal swab

Question 15

Antifungal therapy

Answer 15

Polyenes - amphotericin B bind ergosterol (significant toxicity), currently enclosed in liposomes to make it safer, tends to be second-line

First line antifungal therapy - azoles inhibit ergosterol synthesis, rather safe

Allylamines - terbinafine topical antifungal, inhibits earlier step in sterol synthesis (has liver toxicity when taken orally)

Echinocandins - newest group, end in fungin, inhibit cell wall glucan synthesis, only IV use, predominantly used to treat candida (increasing azole resistance)

Question 16

Fungal site of infections

Answer 16

Superficial, cutaneous, subcutaneous, pulmonary, bloodstream, meningitis

Question 17

Superficial mycoses - where, what species

Answer 17

Involve stratum corneum, malassezia furfur

Question 18

Superficial mycoses - what does it cause, treatment

Answer 18

Chronic hypo or hyperpigmentation (pityriasis versicolor), superficial skin infection, generally treated with topical therapy

Question 19

Cutaneous mycoses - what does it cause

Answer 19

Tinea family (capitis, pedis, cruris, corporis, manus), dermatophytosis, onychomycosis

Question 20

Cutaneous mycoses treatment

Answer 20

Topical azoles, systemic azoles, terbinafine, griseofulvin

Question 21

Subcutaneous mycoses - species, what does it cause

Answer 21

Sporotrichosis - nodular lesion with lymphatic spread (“Rose gardener’s disease”)

Question 22

Subcutaneous mycoses treatment

Answer 22

Itraconazole

Question 23

Endemic mycoses causative agents

Answer 23

Thermally dimorphic fungi (hyphal form in environment, yeast form in tissue)

Question 24

How are endemic mycoses acquired

Answer 24

Inhalation -> pulmonary infection -> dissemination (potentially)

Question 25

Histoplasmosis - what does it cause

Answer 25

Vast majority of primary infection is subclinical | Complications - Pulmonary calcifications, mediastinal lymphadenitis, mediastinal fibrosis

Question 26

Histoplasmosis - characteristic tissue response

Answer 26

Caseating or noncaseating granulomas (also for TB)

Question 27

Histoplasmosis treatment

Answer 27

Amphotericin B, Itraconazole

Question 28

Blastomycosis - where does it disseminate

Answer 28

Skin and bone

Question 29

Blastomycosis - typical inflammatory response

Answer 29

Clusters of neutrophils and noncaseating granulomas

Question 30

Blastomycosis diagnosis

Answer 30

Broad-based budding yeast

Question 31

Candidiasis: Types of infections

Answer 31

``` Mucocutaneous infection (thrush, vulvovaginal candidiasis, esophageal candidiasis) Invasive infection (candidemia) ```

Question 32

What is candida auris associated with

Answer 32

Nosocomial transmission and outbreaks in healthcare settings, multi-drug resistance

Question 33

Cryptococcosis: What does it have a predilection for

Answer 33

CNS

Question 34

Cryptococcosis virulence factor

Answer 34

Polysaccharide capsule - produces brain edema, polysaccharide plug up arachnoid villi

Question 35

When use 5-flucytosine

Answer 35

Initial therapy for cryptococcosis (along with amphotericin B)

Question 36

How get cryptococcosis

Answer 36

Inhaled and disseminates

Question 37

How get aspergillosis

Answer 37

Inhaled

Question 38

What aspergillosis cause

Answer 38

Pneumonia, sinusitis, disseminated infection

Question 39

Aspergillosis histopathology

Answer 39

Septate hyphae, acute angle branching

Question 40

Mucormycosis - how get it

Answer 40

Environmental organisms get inhaled - right circumstances can cause disease

Question 41

Mucormycosis histopathology

Answer 41

Broad, non-septate, right-angle branching

Question 42

Mucormycosis - what does it cause

Answer 42

Pneumonia, rhino-orbital, cerebral disease