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Flashcards in Dermatophytes Deck (45):
1

fungi that infect superficial areas of body, such as hair, skin and nails

dermatophyte

2

Infection of keratinized tissue

dermatophytosis

3

Infections of the head

tinea capitis

4

infections of the body

tinea corporis

5

infections of the beard

tinea barbae

6

infections of the groin (jock itch)

tinea cruris

7

infections of the foot (athlete's foot)

tinea pedis

8

infections of the nail

tinea unguium

9

nail infection by non-dermatophytes

onchomycosis

10

Dermatophyte infections are commonly referred to as "tinea" or "_______"

ringworm

11

why do dermatophytes generally only infect hair, skin and nails?

They use keratin as nitrogen source

12

What is the most common of human fungal infections

dermatophyte

13

What are the three ways to identify a dermatophyte infection?

- Direct physical examination
- Lab examination of specimen (skin scraping, hair, toenail)
- Culture

14

What are 4 Direct Physical Exams

1. Wood's lamp (UV)
2. Potassium hydroxide (KOH)
3. Calcoflour white - fungi fluoresce
4. Exam of hair for ectothrix or endothrix invasion

15

In Wood's Lamp Exam:
- Microsporum in hair fluoresces ________
- Skin with tine versicolor fluoresces ________
- Trichophyton fluoresces _________

- yellow-green
- yellow
- does NOT fluoresce

16

Culture:
- what medium and what does it do?

Primary isolation medium + cyclohexamide to kill skin contaminants (CSAB) (Mycosel or Mycobiotic Agar)

17

Culture:
- incubation time?

2-4 weeks (recommended 30 days)

18

Most identifications are by ______ ______

microscopic morphology (microconidia/macroconidia)

19

Trichophyton infects what?

hair, skin, and nail (especially feet and nails)

20

Trichophyton:
- Microconidia vs Macroconidia

Microconidia: important for identification
Macroconidia: rarely helpful

21

Trichophyton:
- other tests available?
- does it fluoresce with Wood's lamp?

- Biochemical tests available
- does NOT fluoresce

22

Second most common cause of dermatophytosis

Trichophyton rubrum

23

Trichophyton rubrum:
- Reverse

most are cherry red (>3 weeks)

24

Trichophyton rubrum:
- What do they look like?

tiny teardrop microconidia; "birds on a wire"

25

Trichophyton rubrum
- Urease reaction

negative

26

Trichophyton rubrum
- Hair perforation reaction

Negative

27

Trichophyton mentagrophytes:
- 2 types of colonies

- downy: from feet
- granular: infection spread from animals

28

Trichophyton mentagrophytes:
- reverse

May be red/brown (medium dependent)

29

Trichophyton mentagrophytes:
- microscopic mold appearance

- hyphae may be spiral shaped
- tear-shaped microconidia often in grape like clusters
- macroconidia cigar shaped

30

Trichophyton mentagrophytes:
- urease reaction

Positive

31

Trichophyton mentagrophytes:
- hair perforation test reaction

Positive

32

#1 cause of tinea capitis in US (especially children) and wrestlers, hence "tinea gladiotorium)

Trichophyton tonsurans

33

Trichophyton tonsurans:
- Colonies

Buff/brown (May be rust colored on reverse), wrinkled or cratered

34

Trichophyton tonsurans:
- Microconidia appearance

Elongated balloons or stretched teardrops

35

Trichophyton tonsurans:
- grows poorly on most media, growth enhanced by __________

Thiamin (T4 agar vs T1 agar)

36

Trichophyton tonsurans:
- any hair infection?

Endothrix infection (fungus inside hair shaft), hair brakes at scalp ( "Black dot")

37

Trichophyton verrucosum:
- causes tinea ______

Capitus (another cause of "black dot")

38

Trichophyton verrucosum:
- what type of people are at risk

Cattle/dairy workers

39

Trichophyton verrucosum:
- lesions often misdiagnosed as what type of infection

Staph infection

40

Trichophyton verrucosum:
- microscopic appearance

"antler hyphae" and chlamdoconidia "armadillo/rat tails"

41

Trichophyton verrucosum:
- Will it grow at 37°C

- growth is enhanced at 37°C

42

Trichophyton schoenleinii:
- what infection does it cause

- causes favus (tinea capitus) - scarring and permanent hair loss (yellow, thickened, cup shaped crusts)

43

Trichophyton schoenleinii:
- colony appearance

Gray and waxy

44

Trichophyton schoenleinii:
- microscopic appearance

- conidia are rare, club/antler shaped hyphae and "favic chandeliers"
- branching hyphae seen within hairs (tunnels)

45

Trichophyton schoenleinii:
- common in what countries

Appalachia and Scandinavian countries