Unit 3: Fungi Summary

Question 1

In what ways are fungi like humans?

Answer 1

Eukaryotic, heterotrophic

Question 2

Instead of peptidoglycan and a 70S ribosome (bacteria), Fungi have what?

Answer 2

Beta-glucan, ergosterol, 80S ribosome

Question 3

Fungi can grow in what three environments more easily than bacteria?

Answer 3

Drier, Higher osmotic pressure, Colder (more cutaneous and food spoilage)

Question 4

Two main types of fungi and how they reproduce

Answer 4

1. Yeast (single celled, reproduce by budding)

2. Molds (complex reproduction)

Question 5

What is closed mitosis?

Answer 5

Nuclear membrane does not break down in mitosis

Question 6

Filamentous parts of molds are called?

Answer 6

Hyphae

Question 7

The “mats” of molds are called?

Answer 7

Mycelium

Question 8

The fact that fungi have little contagion, drug resistance, and no possibility of eradication are because of what characteristic of fungi?

Answer 8

They are mostly environmental pathogens

Question 9

What is the fungi that is NOT an environmental pathogen?

Answer 9

C. albicans, a yeast! It’s found in normal flora/opportunistic pathogen

Question 10

What are the five types of asexual spores useful for and why are they useful for that?

Answer 10

Diagnosis- they have a distinct microscopic appearance

Question 11

In thermal dimorphism, what grows at 24C and what grows at 37C?

Answer 11

24C - mold, 37C- yeast!

Question 12

Why is thermal dimorphism important to know, in terms of diagnosis?

Answer 12

Yeast form has more immune evasive properties, so dual cultures can be useful for diagnosis

Question 13

How can fungal infection be diagnosed?

Answer 13

PPD, KOH mount, culture on Sabouraud’s agar, PCR for dangerous systemics, serology for epidemiology

Question 14

What type of immune response happens in a fungal infection?

Answer 14

Granulomatous immune response, sometimes suppurative

Question 15

What is mycotoxicosis?

Answer 15

Eating fungal toxins (wrong mushroom/spoiled food) it is NOT fungal infection!!

Question 16

What kind of reaction may occur if someone has fungal allergies?

Answer 16

Asthmatic reaction, may be dangerous

Question 17

What do antifungals target?

Answer 17

Beta-glucan, ergosterol

Question 18

What are some problems with antifungal use in humans?

Answer 18

Toxic, few molecular targets (many of their molecules are too similar to ours)

Question 19

What are the main classes of antifungals?

Answer 19

Polyenes, Azoles, Echinocandins

Question 20

What do polyenes do?

Answer 20

Disrupt cell membranes at ergosterol sites

Question 21

What are characteristics of polyene?

Answer 21

Highly effective, broad spectrum, but TOXIC.

Question 22

What is good/bad about Amphotericin B (polyene)

Answer 22

Amphotericin B is the only one for systemic use and but it’s nephrotoxic :(

Question 23

What do Azoles do?

Answer 23

Inhibit ergosterol synthesis

Question 24

What are characteristics of azoles?

Answer 24

Less toxic, different ones optimally active against different fungi

Question 25

Fluconazole/Diflucan (azoles) are used in treading what?

Answer 25

Candidiasis, cryptococcis

Question 26

What do echinocandins do?

Answer 26

Inhibit beta-glucan synthesis

Question 27

What are characteristics of echnocandins? What is it best against?

Answer 27

Low toxicity, highly effective against candida and aspergillus

Question 28

Which type of mycoses does NOT require thermal dimorphism?

Answer 28

Superficial mycoses (grows on superficial skin layer)

Question 29

Dermatophytosis, caused by 3 different genera of fungi, is an example of what type of mycoses?

Answer 29

Superficial mycoses

Question 30

What are the symptoms of dermatophytosis?

Answer 30

Tinea (jock itch, athlete's foot, ringworm)

Question 31

How is dermatophytosis transmitted?

Answer 31

Fomites or autoinnoculation, as it only infects superficial keratinized structures, produces keritinases

Question 32

How do you diagnosis dermatophytosis?

Answer 32

KOH mount, culture

Question 33

How do you treat dermatophytosis?

Answer 33

treat ALL affected body sites simultaneously with topical anti fungal cream (azoles), alternative is oral griseofulvin

Question 34

How is subcutaneous mycoses caused in general?

Answer 34

Introduced by trauma exposing subcutaneous tissue to soil or vegetation.

Question 35

How does the subcutaneous mycoses travel?

Answer 35

Slow spread from trauma site toward trunk by lymphatics, THERMAL DIMORPHISM!

Question 36

What would be an indicator that a person might have a subcutaneous mycoses?

Answer 36

Have a history of ineffective antibiotic treatment

Question 37

Sporotrichosis is an example of what type of mycoses?

Answer 37

Subcutaneous mycoses

Question 38

What is sporotrichosis' mode of transmission?

Answer 38

The thermally dimorphic fungi of vegetation enters the skin through small injuries (thorns, splinters)

Question 39

What dangerous conditions can be associated with sporotrichosis?

Answer 39

COPD, or if the person is immunosurpressed, disseminated meningitis

Question 40

How do you diagnose sporotrichosis?

Answer 40

Biopsy and culture at room temperature from pus

Question 41

How do you treat sporotrichosis?

Answer 41

Treat with oral azoles, and if it's a serious case, use Amphotericin B (or local surgery)

Question 42

Spores/fungi in the soil inhaled into lungs, Thermal dimorphism, and a range of severity are all characteristics that describe what type of mycoses?

Answer 42

Systemic mycoses

Question 43

Coccidiodes is an example of what type of mycoses?

Answer 43

Systemic mycoses

Question 44

What is special about coccidiodes' thermal dimorphism?

Answer 44

It changes between mold and SPHERULE

Question 45

What mycoses is endemic to the US Southwest?

Answer 45

Coccidiodes

Question 46

What mycoses has mold that grows in wet weather, releases infectious arthrospores in dry weather, and then the spores are inhaled and change form?

Answer 46

Coccidiodes

Question 47

Describe the mild form of coccidiodes | systemic mycoses

Answer 47

60% of people, asymptomatic or flu like clearance by innate immunity, or containment by CMI

Question 48

Describe the moderate form of coccidiodes | systemic mycoses

Answer 48

Valley fever/desert rheumatism, may have pulmonary involvement + erythema nodosum (painful red bumps)

Question 49

Describe the severe form of coccidiodes | systemic mycoses

Answer 49

Major pneumonia or dissemination (either hematogenous spread or intracellular travel via macrophages)

Question 50

How do you diagnose coccidiodes?

Answer 50

Exam, history!!!, PPD, biopsy for spherules, culture, serology for dissemination

Question 51

What will the optimal treatment for an opportunistic mycoses address? (2 things)

Answer 51

The infection AND the underlying problem

Question 52

Cryptococcosis is an environmental type of what mycoses?

Answer 52

Opportunistic mycoses

Question 53

How is cryptococcocis infective?

Answer 53

It can infect when a person has reduced CMI (surpressed host inflammatory response)

Question 54

When and how does cryptococcosis present?

Answer 54

Late in disease b/c inflammatory response complicates diagnosis!! With meningitis and skin nodules or pulmonary symptoms

Question 55

How do you diagnose cryptococcosis?

Answer 55

Diagnose by biopsy, CSF, crag (cryptococcal antigen in blood and CSF)

Question 56

How do you treat cryptococcosis?

Answer 56

Combo of azoles + Amphotericin B