Micro U2 L5.

Question 1

Dermatophytoses: what is it caused by and what do it infect?

Answer 1

dermatophytes = infects skin, hair, nails

Question 2

Which genera of dermatophytoses can you contract from pets?

Answer 2

microsporum

Question 3

What are the three genera of dermatophytoses?

Answer 3

epidermophyton, trichophyton, microsporum

Question 4

Where do dermatophytoses cause infection?

Answer 4

warm human area - cause inflamed circular border of papules and/or vesicles

Question 5

What does hypersensitivity to dermatophytid (circulating fungal antigen) cause?

Answer 5

vesicles on finger

Question 6

How is diagnosis of dermatophytoses made?

Answer 6

PPD with trichophytin; microscopic exam; culture; wood’s lamp

Question 7

How is microscopic exam of dermatophytoses done?

Answer 7

1. scrape affected skin/nail 2. treat with 10% KOH 3. examine remains for hyphae/spores

Question 8

What type of agar is used to dermatophytoses culture?

Answer 8

sabouraud’s agar at room temp

Question 9

What does dermatophytoses show when examined under wood’s lamp?

Answer 9

fluorescence

Question 10

Treatment of dermatophytoses

Answer 10

topical antifungal cream (terbinafine, undecylenic acid, miconazole, tolnaftate; oral griseofulvin; keep skin dry and cool

Question 11

Tinea versicolor organism

Answer 11

malassezia furfur (normal flora - overgrowth)

Question 12

What does tinea versicolor cause?

Answer 12

superficial skin infection (only cosmetic), hypo pigmented areas with slight scaling/itching - most frequent in hot, humid weather

Question 13

How is diagnosis of tinea versicolor made?

Answer 13

take skin scrapings and treat with 10% KOH; examine microscopically for mix of budding yeasts and hyphae

Question 14

Treatment of tinea versicolor

Answer 14

topical miconazole

Question 15

Tinea Nigra organism

Answer 15

cladosporium werneckii

Question 16

Tinea Nigra pathogenesis

Answer 16

spores in soil that enter injury; germinate keratinized skin layers; generate a brown pigment (resembles melanoma)

Question 17

Where is tinea nigra seen?

Answer 17

South US

Question 18

How is diagnosis of tinea nigra made?

Answer 18

skin scarpings, culture on sabouraud’s, treat with 10% KOH - examine microscopically for hyphae

Question 19

Tinea Nigra treatment

Answer 19

topical keratolytic agent (salicyclic acid) plus topical azole

Question 20

What are the cutaneous mycoses?

Answer 20

dermatophytoses, tinea nigra, tinea versicolor

Question 21

How are the subcutaneous mycoses introduced?

Answer 21

by trauma exposing subcutaneous tissue to soil or vegetation

Question 22

Sporotrichosis organism

Answer 22

thermally dimorphic, found in vegetation - seen in gardeners

Question 23

Pathogenesis of sporotrichosis

Answer 23

introduced by thorn puncture -> yeast grow at site and form painless pustule/ulcer -> draining lymphatics form nodules -> symptoms wane and wax (disseminated in immunosuppressed)

Question 24

Sporotrichosis exam

Answer 24

painless pustule or ulcer hand or arm, history of gardening and uneffective antibacterial treatment

Question 25

Labs for sporotrichosis

Answer 25

tissue speciment - round or cigar-shaped budding yeasts - culture at room temp (hyphae with oval conidia in clusters at tip of slender conidiophores (look like daisies)

Question 26

Treatment of sporotrichosis

Answer 26

itraconazole (3-6 months)

Question 27

Chromomycosis organism

Answer 27

dermatiaceous fungi: fonsecaea, phialophora, cladosporium

Question 28

Where is chromomycosis found?

Answer 28

soil in tropics

Question 29

What color are conidia or hyphae of chromomycosis?

Answer 29

gray or black

Question 30

Pathogenesis of chromomycosis

Answer 30

introduced into legs/feet with injury -> gradually progressive subcutaneous disease -> granulomas form as immune system attempts to contain

Question 31

Diagnosis of chromomycosis

Answer 31

exam: wartlike dark colored lesions/crusting abscesses extendign along lymphatics. lab: tissue specimen with dark brown, round fungal cells INSIDE leukocytes or giant cells (granuloma response)

Question 32

Treatment of chromomycosis

Answer 32

oral flucytosine or thiabendazole 6 mo. min; local surgery

Question 33

Mycetoma oraganism

Answer 33

petriellidium or madurella

Question 34

How is mycetoma contracted?

Answer 34

soil through wounds

Question 35

What is seen on exam of mycetoma?

Answer 35

replicating fungi form abscesses; pus containing compact colored granules forms and drains through local sinuses

Question 36

What does mycetoma appear similar to? How are they differentiated?

Answer 36

actinomycosis - need to measure filamentous structures on stained slides (mycetoma will be larger)

Question 37

Mycetoma treatment

Answer 37

attempt antibiotic and anti fungal therapy (oral azalea plus IV amphotericin B); surgical excision of abscesses necessary usually

Question 38

Where is mycetoma found?

Answer 38

tropical areas

Question 39

What are the subcutaneous mycoses?

Answer 39

sporotrichosis, chromomycosis, mycetoma

Question 40

Candidiasis

Answer 40

an opportunistic cutaneous mycosis

Question 41

Candidiasis primary organism

Answer 41

candida albicans

Question 42

What are common symptoms of candidiasis overgrowth?

Answer 42

thrush, vaginitis, esophagitis, diaper rash, chronic mucocutaneous candidiasis

Question 43

How does candidiasis appear on microscope?

Answer 43

oval yeast with single bud, may also appear as pseudohyphae

Question 44

Virulence factors for candidiasis

Answer 44

adhesins, acid proteases, phenotypic switching

Question 45

What is a predisposition for thrush? Vaginitis?

Answer 45

thrush: steroid inhalers for asthma; vaginitis: antibiotics, diabetes

Question 46

Folliculitis

Answer 46

boil at the base of hair follicle seen in candidiasis

Question 47

When does systemic candidiasis appear

Answer 47

AIDS, IL-17 deficient

Question 48

Treatment of candidiasis

Answer 48

begin with symptoms on outside of body - add more as overgrowth becomes more serious

Question 49

Candidiasis exam

Answer 49

rash, wet, itch surfaces; relevant predisposition

Question 50

Candidiasis lab

Answer 50

exudate or tissue samples: budding yeasts and psudohyphae (gram-positive - visualized by calcofluor-white stain) - culture: large colonies similar to bacterial on agar - in serum = germ tubes