fungi

Question 1

fungi are?

Answer 1

mold
yeast
mushrooms

Question 2

why are fungi harder to kill than bacteria?

Answer 2

Fungi are eukaryotic so they can’t be treated with antibiotics

Question 3

how do yeast grow?

Answer 3

by budding

Question 4

how does mold grow?

Answer 4

by making mycelium which is composed of hyphae and conidia

Question 5

what is targeted for chemotherapy in fungi?

Answer 5

ergosterol in the membrane

Question 6

what is the rigid cell wall of fungi made of?

Answer 6

inner glucan

outer mannan

Question 7

what are the 2 types of hyphae?

Answer 7

septate=separates different parts of hyphae

nonseptate=big long tube with many nuclei

Question 8

hyphae vs pseudohyphae

Answer 8

Hyphae = mycelium, multinucleated
Pseudeohyphae = psuedomycelium, long chains of yeast cells, mononucleated

Question 9

Describe fungi sexual cycle

Answer 9

both genders secrete pheromones
it signals Ras protein to induce sexual cycle
both cells grow towards each other
both cells fuse
zygote is created
undergoes meiosis to make 2 male and 2 female spores

Question 10

what are the 4 fungal types?

Answer 10

Ascomycetes - septate hyphae and yeilds meiotic products in sac or ascus
Basidiomycetes- septate hyphae and yeilds meiotic products on base or basidium
Zygomycetes - nonseptate hyphae and large diameter hyphae and zygospore forms when 2 haploids fuse
Deutermyces - unclassified and sexual cycle not discovered

Question 11

what is temperature dimporphism?

Answer 11

fungi can grow as mold in Sabourad’s agar (colder)

or fungi can grow as yeast in blood (wamer)

Question 12

What does fungi stain as?

Answer 12

Fungi are not classified as gram positive or gram negative but it takes up crystal violet

Question 13

most fungi are saprobes. What are saprobes?

Answer 13

decomposers
degrade and live on dead organic matter
can live on just glucose, NH3, SO4, PO4, trace elements
cultured on sabourad’s agar made of agar, glucose, protein hydrolysate (peptone)

Question 14

what are the antifungal drug mechanisms?

Answer 14

polyenes - hole in ergosterol
Imidazoles - inhibits cytochrome P450 enzyme in ergosterol synthesis
Terbinafine - inhibits squalene epoxidase (monooxygenase)
Echinocandins - inhibit cell wall synthesis by inhibiting glucan synthesis
Flourocytosine - inhbits RNA/DNA synthesis
Griseofulvin - inhibits microtubules

Question 15

what are the antifungal types of drugs and examples?

Answer 15

polyenes - amphotericin B and Nystatin
Imidazole - clotirimazole and fluconazole
Terbinafine - Lamsil
Echinocandins - caspofungin (cancidas)
Flourcytosine - ancabon

Question 16

list of superficial mycotic (fungal) infections

Answer 16

various tineas (ringworms)
favus
black and white piedra
black palms

Question 17

tineas (ringworms) examples?

Answer 17

Tineas capitis - (on scalp)
Tineas cruris (penis)
Tineas pedis - (athletes foot)
Tineas barbi - (on beard)
Tineas corporis - (body)
Tineas onychomnycosis - (nails)

Question 18

what are dermatophytes?

Answer 18

fungi that require keratin for growth

Question 19

what are the 3 genera of dermatophytes?

Answer 19

Tinea infections are caused by the dermatophytes trichophyton, microsporum, and epidermophyton

Question 20

which dermatophytes are slow growing?

Answer 20

Trichophyton
epidermophyton
microsporum

Question 21

properties of dermatophytes

Answer 21

grow faster in lipids
don’t grow above skin temperature 34 degrees
produce proteases to degrade keratin
produce hyphae and macroconidia
produce spores which are aleurospore
mostly aerobic and sometimes facultative anaerobic
never obligate anaerobe

Question 22

what is the more severe form of tineas pedis (athletes foot)?

Answer 22

nail involvement
bleeding
bacterial infection

Question 23

what does tinea unguium onchomycosis require?

Answer 23

infects nail bed so it requires systemic treatment

Question 24

what fungi cause Tineas?

Answer 24

Favus - Tinea favosa = favic chandeliers and scales on scalp
Tinea versicolor = Mallesezia globosa and M. furfur, dimorphic fungus, normal flora, fungus inhibits melanin producing light spots, sometimes spots are darker
Tinea Nigra = exophiala sp.

Question 25

how to detect superficial dermatophytosis?

Answer 25

KOH preps of skin scraping

Question 26

what is the dermatophytid (id) response?

Answer 26

allergic reaction on body with pustules by the secreted foreign protein which causes itching But there is no fungi in this part, even if you do a skin scraping if you see this id response, you look elsewhere on body for dermatophyte infection to find fungus on skin scraping

Question 27

favus

Answer 27

Trichophyton schoenleinii

Question 28

Tinea versicolor

Answer 28

Mallesezia globosa or M.furfur

Question 29

sporotirchosis

Answer 29

sporotrichum schenkii (sporothrix)

Question 30

subcutaneous infection list of species

Answer 30

``` pseudoallescheria exophalia fonsecaea phialaphora cladosporium ```

Question 31

list of systemic mycotic infections

Answer 31

histoplasmosis - granuloma in lungs and fungi can grow in granuloma NA blastomycosis broad based large yeast cell SA blastomycosis multiple budding yeast coccidiodomycosis - spores inhaled respiratory illness (mold and spheules) cryptoococcosis - encapsulated yeast and no dimorphism

Question 32

systemic mycotic infection characteristics

Answer 32

transmitted by mold spore or yeast inhalation respiratory tract infection that leave calcified granulomas in IC pt. rare severe respiratory syndrome or skin lesions, meningitis, organ involvement diagnosed by observing organism in infected tissue, immunoassays, PCR treated with imidazole or amphotericin B

Question 33

histoplasmosis x ray shows

Answer 33

primary lung infection with consolidation then after healing you are left with granulomas not due to tumor. sometimes live fungal cells grow in granuloma

Question 34

where are major incidence of histoplasmosis?

Answer 34

midwestern river valleys

Question 35

properties of histoplasmosis

Answer 35

``` facultative intracellular (grows in cells like lymph node or vesicle like macrophage) prevents lysosome from killing it and thats how it grows in macrophage ```

Question 36

NA blastomycosis

Answer 36

skin lesion dimorphic broad-based very large yeast cell east coast

Question 37

SA blastomycosis

Answer 37

skin lesion dimorphic multiple budding yeast cells septate hyphea on mold phase

Question 38

coccidiomycosis

Answer 38

in soil desert areas west coast spherules in infected tissue (infective stage) = spherule stage is 5 days arthrospores in mold stage from sabourads agar can be inhaled no yeast phase short hyphae in lung

Question 39

cryptococcus neoforms

Answer 39

``` encapsulated yeast no temperature dimorphism grows in pigeon and other bird droppings observed in india ink and birdseed agar shows pigmented yeast skin lesions can go to brain ```

Question 40

list of opportunitistic fungal infections

Answer 40

candidiasis aspergillosis zygomycosis pneumocystal pneumonia

Question 41

candida albicans

Answer 41

``` vaginal smear a yeast oral thrush affects skin, retina, and nail dimorphic germ tube formation in blood serum chlamydospores on corn meal agar ```

Question 42

candida auris

Answer 42

antifungal resistant oral thrush opportunistic

Question 43

pneumocystis pneumonia

Answer 43

``` specimen from lung biopsy normal flora airborne treat with trimethoprim-sulfamethoxazole opportunistic infection used to be protozoan, now reclassified as fungus ```

Question 44

aspergillus flavus

Answer 44

``` different colonial morphologies fast growing lethal, ubiquitous granuloma in lung grows in blood vessel ```

Question 45

zygomycetes

Answer 45

mucor sp. | large diameter hyphae visible on agar plate

Question 46

mycotoxicosis and sick building syndrome

Answer 46

nonspecific symptoms mold poisons and allergens are the causes stachybotrys sp. aspergillis sp.

Question 47

list of mycotoxicosis

Answer 47

amanitis phalloidis psilocybe cyanescens aspergillus flavus

Question 48

purely opportunisitic fungal infections?

Answer 48

candidiasis aspergillosis zygomycosis pneumocystal pneumonia