Dermaphytes

Question 1

T/F: Dermaptophyte infections are the most common fungal infections in vet med

Answer 1

TRUE

Question 2

Where do dermatophytes have a tropism to?

Answer 2

Keratin

superficial keratinized epithelium- hair and nails

Question 3

Are dermatophytes zoonotic?

Answer 3

YES

Question 4

T/F: Dermatophyte infections are typically self limiting

Answer 4

TRUE

Question 5

What factors predispose animals to dermatophyte infections?

Answer 5

Young, poor nutrition, high humidity, scratching/rubbing

Question 6

When are cattle the most predisposed to dermatophyte (specifically ringworm) infections?

Answer 6

In the winter due to low UV light - when housed indoors

Question 7

T/F: Anthropophilic is a term used for dermatophytes that infect arthropods

Answer 7

FALSE

anthropophilic = human reservior

Question 8

Who or what are the reservoirs for zoophilic dermatophytes and geophilic dermatophytes?

Answer 8

Zoophilic = animals

Geophilic = soil or environmental

Question 9

What are the three species of ring worm most commonly seen in dogs, cats, and humans?

Answer 9

Microsporum canis
Microsporum audouinii
Microsporum gypsium

Question 10

T/F: If a cow has a ring worm infection, it is most likely caused by Trichophyton verrucosum

Answer 10

TRUE

Question 11

What is the agent of ring worm for horses, and the agent for pigs?

Answer 11

Horses - Trichophyton equinum

Pigs - Microsporum nanum

Question 12

What are characteristics of a dermatophyte infection?

Answer 12

slowly expanding circle of alopecia and desquamated epithelium - central area will have hair regrowth

Question 13

When testing for ring worm, from where should you collect your sample?

Answer 13

The outer edge of the lesion - NOT THE CENTER

Question 14

T/F: Dermatophytes always cause superficial skin infections with alopecia

Answer 14

False

They do MOST of the time but “not all ringworm is classic”

Sometimes they can form granulomatous and nodular lesions

Question 15

Who are the main carriers of mycosporum canis?

Answer 15

CATS - often are asymptomatic carriers

*most ringworm infections of cats and dogs is due to - microsporum canis and M. gypsium

Question 16

Does Trichophyton mentagrophytes have a wide or narrow host range when compared to micosporum species?

Answer 16

WIDER HOST RANGE

Question 17

What is a kerion lesion?

Answer 17

Nodular lesion caused by dermatophytes, localized, or generalized. Often with furnuculosis

Question 18

If a Persian cat presents with a SQ nodule - what may you expect it to be? (think fungus)

Answer 18

Pseudomycetoma - caused by Microsporum canis

Question 19

Does the species of dermatphyte matter for treatment?

Answer 19

NO

It matters for controlling infection - so you know who the proper host is

Question 20

The most common animal humans get ringworm infections is from…?

Answer 20

CATS

Question 21

T/F: Mycosporum canis infection will glow in the dark and this is used to diagnose infections

Answer 21

FALSE

Does not glow in the dark, but you can used a Woods Lamp to detect fluorescence of microsporum infections

Question 22

T/F: There is no preparatory step to be done to the lesion before collecting a sample

Answer 22

FALSE

disinfect the area with 70% alcohol

then pick hairs of affect lesion and send it DRY. Tubes should not be tightly closed to prevent moisture

Question 23

What might you see on a microscopic evaluation of a hair sample of a patient with ringworm?

Answer 23

Large number of spores - arthrocondia on broken hairs

Question 24

You’re tech looks at a sample of hair from a patient with ringworm under the microscope and tells you she sees endothrix arthrocondia; what does that mean? Why is it imporant

Answer 24

She is describing the location of the spores
Ectothrix = outside the hair follicle
Endothrix = inside the hair follicle

This can be used for species identification

Question 25

T/F: Performing your own in house culture is an acceptable way to diagnose ringworm infections

Answer 25

TRUE

perform culture - if agar changes color (Red) and grows - they you perform a scotch tape prep and use lactophenol cotton blue staining to confirm

OR - can use pre made Dermatophyte test media

Question 26

Who does Microsporum gallinae infect? What does it cause?

Answer 26

Chickens - causes Favus

Causes white lesions on comb and wattles - very itchy and irritating

Question 27

Is treating/disinfection the environment recommended when dealing with a ring worm infection?

Answer 27

YES

clean/disinfect environment - clean bedding etc

Question 28

Are there vaccines available for ringworm?

Answer 28

Yes - available for cats and cattle

not widely used

Question 29

Where does Malassezia app have tropism for and what do they cause?

Answer 29

They are lipophilic yeast - like oily areas

***Often cause ear infections - otitis externa and superficial moist dermatitis

Question 30

T/F: Dermatophytes sometimes cause systemic infections

Answer 30

FALSE