Fungi

Question 1

what do fungi have in their plasma membranes instead of cholesterol?

Answer 1

ergosterol

Question 2

what kingdom are fungi from?

Answer 2

eukarya

Question 3

what kind of fuel do fungi need to survive and what term defines that?

Answer 3

preformed organic energy supplying compounds, heterotrophic

Question 4

what type of ribosomes and cell walls do fungi have?

Answer 4

chitin and beta glucan cell walls

80S ribosomes

Question 5

what is a major barrier in antifungal treatment?

Answer 5

toxicity- fungi have more similar molecules to humans (few possible targets)

Question 6

what are some differences in where fungi can live compared to bacteria? What implication does this have on where they grow

Answer 6

they can live in more extreme conditions- drier, higher osmotic pressure and colder
Tend to be more cutaneous infections and grow in refrigerated food

Question 7

what are the two main types of fungi?

Answer 7

yeasts and molds

Question 8

describe the structure of a mold.

Answer 8

mats (mycelia) of fibers (hyphae)

Question 9

describe a yeast

Answer 9

a single celled fungus that reproduces by budding

Question 10

describe the reproduction cycle of a fungus

Answer 10

very complicated reproduction pathways involving multiple forms of fungus and possibly different types of reproduction

Question 11

what structure makes identifying fungi easier microscopically?

Answer 11

there are 5 types of asexual spores with distinct appearance. can help aid diagnosis

Question 12

explain thermal dimorphism and what implications does it have for infection?

Answer 12

when a fungus grows at a mold at 24C and as a yeast at 37C- grow as yeasts in the body

Question 13

what are the two hallmark immune responses to fungal infection?

Answer 13

granulomas and suppurative exudate (pus)

Question 14

how are fungal pathogens transmitted and what implications does it have on treatment?

Answer 14

grow in the environment and cannot be passed from person to person
means there is little drug resistance but also infections cannot be eradicated

Question 15

what type of yeast is normal flora?

Answer 15

C albicans

Question 16

what is mycotoxicosis?

Answer 16

syndrome caused by eating fungal toxins (not a fungal infection)

Question 17

what type of hypersensitivity response is common with fungal infections?

Answer 17

type 1 (allergies)

Question 18

what skin test is used to diagnose fungal infection?

Answer 18

PPD type test

Question 19

why is KOH added to fungal microscopy samples?

Answer 19

to kill all human cells

Question 20

what medium is fungus cultured on?

Answer 20

Sabouraud’s agar

Question 21

if a patient has a dangerous systemic fungal infection, what is the quickest way to diagnose it?

Answer 21

PCR amplification and molecular testing

Question 22

What tests are used for systemic fungal infections?

Answer 22

PCR and serology

Question 23

what are the major classes of antifungal agents?

Answer 23

polyenes, azoles and echinocandins

Question 24

what is the mechanism of a polyene drug and what is the major type?

Answer 24

disrupt cell membrane at ergosterol insertion sites

Amphotericin B

Question 25

what is the mechanism of azoles?

Answer 25

to inhibit ergosterol synthesis

Question 26

what is the mechanism of echinocandins?

Answer 26

inhibits beta- glucan synthesis

Question 27

what is the most effective broad spectrum antifungal class?

Answer 27

polyenes

Question 28

why is amphotericin B only used in life threatening fungal infections?

Answer 28

it is nephrotoxic

Question 29

what antifungal is approved for use on pregnant women with systemic fungal infection?

Answer 29

Amphotericin B

Question 30

what are the two major Azoles and what fungi are they effective against?

Answer 30

Diflucan and Fluconazole | candidiasis and cryptococcosis

Question 31

what is the major benefit of Echinocandins?

Answer 31

low toxicity

Question 32

what fungal infections are Echinocandins effective against?

Answer 32

candida and aspergillus

Question 33

which types of mycoses do not require thermal dimorphism?

Answer 33

superficial mycoses

Question 34

what are the symptoms of superficial mycoses?

Answer 34

minor symptoms of itch and discoloration

Question 35

what is used to treat superficial mycoses?

Answer 35

topical azoles or oral griseofulvin | treat all sites simultaneously

Question 36

what is fungal infection of the skin called and which structures does it infect?

Answer 36

dermatophytosis | infects skin, hair and nails (keratinized structures)

Question 37

what are the symptomes of dermatophytosis called and where are the major subtypes commonly called?

Answer 37

Tinea | jock itch, athlete's foot and ringworm

Question 38

how are tineas transferred?

Answer 38

fomite or autoinnoculation

Question 39

how are dermatophytoses diagnosed?

Answer 39

KOH microscopy mount and culture

Question 40

how is a subcutaneous mycosis contracted?

Answer 40

trauma exposing subcutaneous tissue to the environment (usually thorn pricks and splinters)

Question 41

how do subcutaneous mycoses spread?

Answer 41

through the lymphatics towards the trunk

Question 42

what is a common complaint that patients will have with subcutaneous mycoses?

Answer 42

ineffective treatment with antibiotics

Question 43

how are subcutaneous mycoses treated?

Answer 43

oral azoles | serious cases- amphotericin B and local surgery

Question 44

what is sporotrichosis and what organism is it caused by?

Answer 44

it is a subcutaneous mycosis caused by sporothrix spp

Question 45

in what two cases can Sporotrichosis become a pulmonary infection?

Answer 45

if the patient has COPD or has been treated long term with corticosteroids

Question 46

what is a potential consequence of sporotrichosis infection with an immunosuppressed patient?

Answer 46

dissemination and meningitis

Question 47

how is sporothrix spp diagnosed?

Answer 47

biopsy and culture at room temp from pus

Question 48

how does one contract a systemic fungal infection?

Answer 48

inhaling spores (not person-person transmissible)

Question 49

what is the range of severity for a systemic mycosis?

Answer 49

asymptomatic clearance to death

Question 50

a systemic mycosis may mimic what type of infection? How are they differentiated in terms of exposure

Answer 50

TB | exposed to american dirt, not foreign crowds

Question 51

what is coccidioides and where is it endemic?

Answer 51

a thermally dimorphic fungus that can cause systemic infection. endemic to US southwest and latin america

Question 52

how does coccidioides grow in the following types of weather and when is it transmitted to people? Wet and Dry

Answer 52

Wet weather-grows mold | Dry weather- mold dries and arthrospores are released (infectious)

Question 53

60% of coccidioides infections results in what?

Answer 53

asymptomatic or flulike clearance by innate immunity or containment by CMI

Question 54

what are the two diseases caused by mild infection by coccidioides and what are they characterized by?

Answer 54

valley fever and desert rheumatism | pulmonary infection and erythema nodosum

Question 55

what characterizes a severe coccidioides infection?

Answer 55

major pneumonia or dissemination in blood or by marophages

Question 56

what are the risk factors for severe coccidioides?

Answer 56

old age, black or phillipino, late in pregnancy, immunocompromised and occupational exposure

Question 57

when is coccidioides infection treated and how?

Answer 57

if predisposed to complications- oral azoles meningitis- fluconazole pregnant or disseminated- amphotericin B

Question 58

the severity and disease caused by an opportunistic mycosis is majorly due to what factor?

Answer 58

the patient's pre existing conditions

Question 59

optimal treatment of an opportunistic infection does what?

Answer 59

treats the infection and the underlying condition

Question 60

cryptococcus causes what type of infection?

Answer 60

opportunistic mycosis

Question 61

what host characteristic allows an infection of cryptococcus?

Answer 61

reduced CMI

Question 62

what routine bloodwork finding is characteristic of cryptococcosis?

Answer 62

normal results with no inflammatory markers

Question 63

when do patients typically present for a cryptococcosis infection?

Answer 63

late in disease with meningitis and skin nodules or pulmonary symptoms

Question 64

how is cryptococcosis diagnosed?

Answer 64

biopsy, CSF or crag (serotyping)

Question 65

how is cryptococcosis treated?

Answer 65

a combination of azole and amphotericin B while treating the underlying condition