Test 1: Dermatophytes

Question 1

Dermatophyte important virulence factors include

Keratinase, Elastase, and Collegenase

which are _____ enzymes

Answer 1

proteolytic enzymes

Question 2

Dermatophyte proteolytic enzymes help provide nutrients by

Answer 2

digesting host tissues

Question 3

Dermatophytes include different strains of what 2 genuses of fungi?

Answer 3

Trichophyton and Microsporum

Question 4

The availability of ______

plays an important role in tissue tropism of

dermatophytes

Answer 4

IRON

Question 5

Dermatophytes synergize with what bacteria?

Answer 5

Staphylococcus spp.

Question 6

Trace the pathogenesis of a dermatophyte infection

Answer 6

**arthroconidium **enters via stratum corneum

Hyphae and arthroconidia germinate

Hair invasion and germination of spores

Hyphal invasion and growth in the hair cortex

Ectothrix on the ouside of the hair shaft

Question 7

In the parasitic stage of dermatophytes, only

______ and ______ are seen

Answer 7

hyphae and arthroconidia

seen in parasitic stage

of dermatophyte infection

Question 8

Dermatophytes cause _________

Answer 8

RINGWORM

Question 9

In a dermatophyte infection, initially there is little response.

But in the secondary phase, there is an inflammatory response and _________ form

Answer 9

KERION

local plaques that may resemble skin tumors

Question 10

What is tinea synonymous with?

Answer 10

tinea = ringworm

Question 11

What is the main immune response to infection by dermatophytes?

Answer 11

HYPERSENSITIVITY

(Humoral and Cell Mediated, but CMI is more important)

Question 12

T/F

Vaccines exist for protection against Microsporum and Trichophyton (dermatophytes)

Answer 12

TRUE!!

but controversial and variably effective

Question 13

Microsporum audouinii and Microsporum canis

are detected using

_____________

Answer 13

Wood’s Lamp

Question 14

Why do

*M. audouinii and M. canis *

**fluoresce green **under a Wood’s Lamp?

Answer 14

Because they have a certain

tryptophan metabolite

Question 15

Approximately what percent of cases will be positive and fluoresce green?

Answer 15

~60%

*M. canis *and M. audouinii

Question 16

What specimen need to be collected in order to test for

Dermatophytes?

Answer 16

Skin scraping

and

Hair

Question 17

Most dermatophytes grow at 25 - 30C

EXCEPT FOR

___________________

which grows at 37C

Answer 17

T. verrucosum

Question 18

In which species of dermatophyte is MACROCONIDIA usually absent?

Answer 18

Macroconidia absent in

Trichophyton

Question 19

What type of dermatophyte has a

thick, rough wall?

Answer 19

Microsporum

Question 20

In what type of dermatophyte is

MICROconidia

usually absent?

Answer 20

Microconidia absent in

Microsporum

Question 21

What is the sexual form of Microsporum called?

Answer 21

Nannizzia

Question 22

What is the sexual form of Trichophyton called?

Answer 22

Arthroderma

Question 23

Molecular diagnosis of dermatophytes include what 3 things?

Answer 23

Chitin synthase 1 gene

Internal transcribed spacer region

Sequence of DNA encoding 28S (large ribosomal subunit)

Question 24

How are dermatophytes treated and controlled?

Answer 24

Affected areas are first clipped

Combined topical and systemic treatment

(^{with griseofulvin and ketoconazole})

Cleaning of environment using iodine, phenol or chlorine disinfectants

Also, must isolate infected animals

Question 25

Is there a vaccine to prevent dermatophytes?

Answer 25

YES

but only for T. verrucosum and only in Europe