Fungal Infections

Question 1

What are the 4 major classifications of cutaneous fungal infections?

Answer 1

• Superficial cutaneous mycoses
• Subcutaneous mycoses
• Dimorphic systemic mycoses
• Opportunistic mycosis

Question 2

What are the 3 main classes of superficial cutaneous mycosis?

Answer 2

Dermatophytosis (tinea)
Candidiasis
Tinea versicolor

Question 3

What are the three major classes of dermatophytes?

Answer 3

Trichophyton
Epidermophyton
Microsporum

Question 4

How do dermatophytes get nutrition?

Answer 4

digest keratin

Question 5

What diseases do dermatophytes cause?

Answer 5

• Tinea capitis
• Tinea corporis
• Tinea cruris
• Tinea pedis
• Onchomycosis

Question 6

Why do dermatophytes cause very superficial infection?

Answer 6

survive in cool, moist environment

Question 7

What does annular mean?

Answer 7

forms rings that are more clear in the center (with scaly, erythematous papule on outer rim)

Question 8

What is tinea cruris?

Answer 8

jock itch

Question 9

What is tinea pedis?

Answer 9

athlete’s foot

Question 10

What is a moccasin distributin of tinea pedis?

Answer 10

sides of feet and hard part of bottom of foot

Question 11

What is onychomycosis?

Answer 11

fungal infection of toe nails or finger nails

Question 12

Are dermatophytes the only organisms that cause onychomycosis?

Answer 12

NO- candida and molds can also cause it!

Question 13

What is the causative agent of tinea versicolor?

Answer 13

malassezia spp.

Question 14

What is malassezia?

Answer 14

Dimorphic yeast–when it acts as hyphae, it causes tinea versicolor. In yeast form, it is a normal inhabitant of the skin.

Question 15

How does tinea versicolor occur?

Answer 15

Malassezia releases azaleic acid that inhibits the production of melanin!

Question 16

How do you tell the difference between tinea versicolor and pityriasis rosea?

Answer 16

pityriasis is a scaly problem and lines up along the skin lines while tinea versicolor leads to pigment problems and does NOT follow skin lines

Question 17

What does tinea versicolor look like under a KOH stain?

Answer 17

yeasts AND hyphae (spaghetti and meatballs)

Question 18

What does candidiasis look like in KOH stain?

Answer 18

spores and pseudohyphae

Question 19

How might you tell the difference between candidiasis and malassezia?

Answer 19

fungal culture

very hard to tell the difference with KOH

Question 20

What is peronychia?

Answer 20

yeast infection next to nail

Question 21

What is perleche?

Answer 21

angular infection in corner of mouth

Question 22

What is intertrigo?

Answer 22

inflammation of the skin folds

Question 23

What is a helpful clinical clue that you are looking at candidiasis?

Answer 23

satellite macules and pustules

Question 24

What features would have you favor candidiasis over jock itch in the GU area?

Answer 24

candidiasis involves the scrotum and has lack of annular morphology!

Question 25

Is diaper dermatitis always due to candidiasis?

Answer 25

NO! can also be irritant contact dermatitis, seborrheic dermatitis, and psoriasis

Question 26

What is first line therapy for tinea corporis?

Answer 26

topical azole | allylamines (Terbinafine)

Question 27

What is the MOA of allylamines and azoles?

Answer 27

inhibit ergosterol and cell membrane synthesis

Question 28

What is the MOA of griseofulvin?

Answer 28

inhibits microtubule formaiton and inhibits mitosis (binds to tubulin)

Question 29

What is the MOA of nystatin?

Answer 29

direct toxicity to ergosterol in cell membrane (punches holes)

Question 30

What are the 2 different ways hair is infected by dermatophytes?

Answer 30

Ectothrix and Endothrix (inside of the hair shaft)

Question 31

What is a helpful hint you are looking at tinea capitis?

Answer 31

little black dots on the scalp

Question 32

What is the clinical presentation of tinea capitis?

Answer 32

- round area of hair loss - scaly - broken off hairs

Question 33

What is a kerion?

Answer 33

acute inflammatory version of tinea capitis where you get swollen lesions on the scalp (can result in scarring and permanent hair loss)

Question 34

What is seborrheic dermatitis?

Answer 34

NOT an infection--rash that comes out around the eyebrows and nose (very scaly)

Question 35

What causes seborrheic dermatitis?

Answer 35

malassezia colonization that causes inflammation in predisposed individuals

Question 36

What are some examples of subcutaneous mycoses?

Answer 36

sporotrichosis chromoblastomycosis zygomycosis

Question 37

What is the presentation of sporotrichoid spread?

Answer 37

fungal infection that travels through the lymphatics and ulcerate into the skin

Question 38

What is the cause of sporotrichosis?

Answer 38

Dimorphic fungus (acts as a pathogen in its hyphae form!) As a yeast, if forms an asteroid body

Question 39

What is a mycetoma?

Answer 39

madura foot caused by true fungi or fillamentus/true bacteria--deep seated infection (due to foot wound) that the body cannot clear and causes deep seated plaques

Question 40

What features do all mycetomas have?

Answer 40

- tumefaction (edema) - draining sinuses - Grains or granules

Question 41

Where do you see zygomycosis lesions present?

Answer 41

in nasosinus area and invades blood vessels

Question 42

What are the systemic dimorphic mycoses?

Answer 42

blastomycosis (verrucous plaques around nose) coccidiomycosis (HIV patients) histoplasmosis (around nose and mouth)

Question 43

What is the major presentation of systemic dimorphic mycoses? LOOK BACK

Answer 43

all of then can present as primary cutaneous lesions (but this is less common that deep seated ????

Question 44

What are some examples of opportunistic fungal infections?

Answer 44

Candidiasis

Question 45

What does cryptococcosis look like on the skin?

Answer 45

disseminated lesions that can mimic molluscum contagiosum (but many more!)

Question 46

What is a classic opportunistic fungal infection of burn victims?

Answer 46

aspergillosis