Cutaneous Fungal Disease

Question 1

lipophilic budding yeasts that are commensals but secondary colonizer in conditions of barrier dysfunctions (atopy, food sensitivity, seborrhea oleosa)

Answer 1

Malassezia Pachydermatis

Question 2

How does Malassezia Pachydermatis typically overgrow

Answer 2

secondary to underlying skin disease
-atopy
-food sensitivity
-seborrhea (oleosa)
*no immunosuppression

prefers warm, moist areas, reduced UV light exposure (folded reasons)

Question 3

Where are you most likely to find Malassezia Pachydermatis

Answer 3

Skin folds
-prefers warm, moist areas with reduced UV light exposure

Question 4

Malassezia Pachydermatis overgrowth is not associated with

Answer 4

immunosupression

Question 5

When doing cytology, how do you typically quantify Malassezia Pachydermatis

Answer 5

1+ : some in every field
2+: about 10 in every field
3+ : 30-50 in every field
4+: Malassezia all over the field

Question 6

What is the clinical presentation of Malassezia Pachydermatis

Answer 6

erythema, bronze colored greasy exudate (seborrhea oleosa) PRURITUS (inflammatory)

occur: interdigital, claw folds, mucocutaneous junctions, ventral neck, skin folds, ears

Question 7

How do you differentiate Malassezia Pachydermatis from porphyrin staining (licking) when it occurs at the claw folds

Answer 7

tape or scrape these
(easier to do from yeast- exudate)
bacterial paronychia possible as well

Question 8

How do you diagnose Malassezia Pachydermatis

Answer 8

1) impression smears of moist or waxy surfaces
2) Tape for dry lesions

stain with diff quic

examine under oil immersion, quantify, record
>1-3 yeast/hpf on skin and >5 yeast/hpf in the ear = abnormal

Question 9

Some indiviauls with atopy may become _____ to malassezia nad its by products

Answer 9

hypersensitive

even though there is normal or low numbers of yeast it is problematic

if clinical signs consistent any any more than an occasional Malassezia/hpf then treat!

Question 10

How do you treat Malassezia Pachydermatis

Answer 10

Topicals*
1) Shampoo
-2% chlorhexidine, 2% miconazole
-2% chlorhexidine, 1% ketoconazole
q2-3 days for 2-4 weeks then once-twice weekly maintenance

2) Wipes: acetic acid, boric acid (Malacetic Wipes, dechra), 2% miconazole, 2% chlorhexidine (Miconahex +Triz, Dechra)
BID for 2-4 weeks then twice weekly for maintenance

3) Sprays or Mousses:
2% miconazole, 2% chlorexidine
BID for 2-4 weeks, then twice weekly for maintenance

Question 11

When might you consider systemic treatment for malassezia

Answer 11

-Widespread disease
-Owner unable to perform topical treatment

initial: 2-4 weeks
1) ketoconazole
2) *Terbinafine (pulse therapy) - less likely to have hepatotoxicity
or itraconazole or fluconazole

Question 12

What are the three causes of follicultis

Answer 12

1) Bacterial pyoderma
2) Dermatophytosis
3) Demodex

Question 13

What is the natural host of Microsporum canis

Answer 13

Cats

Question 14

What are 3 common dermatophytosis species

Answer 14

1) Microsporum canis (most common and cats are natural host)
2) Nannizzia gypsea (formerly Microsporum gypseum)
natural habitat in the soil
3) Trichophyton mentagrophytes
Natural host: rodents

Question 15

T/F: all dermatophytosis is zoonotic

Answer 15

true

Question 16

What is the natural host of Trichophyton mentagrophytes

Answer 16

rodents

Question 17

Where is Nannizzia gypsea found

Answer 17

natural habitat: soil

Question 18

Dermatophtosis is common in _____ and uncommon in _____

Answer 18

common in cats
uncommon in dogs

Question 19

Microsporum canis

Answer 19

considered the most contagious of the dermatophytosis
cats can be asymptomatic carriers

risk factors: contact (groups)- individuals, fomites
Immunocompromised (young, debilitated)

Question 20

What lesions are associated with dermatophytes

Answer 20

alopecia
collarettes
scale crust

looks a lot like other dermatologic diseases

Question 21

What is the most common presentation of dermatophytes in dogs specifically

Answer 21

Fungal Kerion
-Dermatophytic furunculosis
-Face or distal limb
-Focal
-This wont fluoresce
-Any species: M canis, N. gypsea, T. metagrophytes

Question 22

T/F: Fungal kerions in dogs will fuoresce

Answer 22

False

Question 23

How many M. canis cases will fluoresce under a wood’s lamp

Answer 23

30-80% of the hair shafts will glow, ignore fibers, crusts, medications, other colors

If it glows, you are not done. Collect these hairs for cytology or culture

Question 24

If hairs glow under wood’s lamp, what should you do to confirm M. canis

Answer 24

collect hairs for cytology/culture

Trichogram: use mineral oil, no need for stain, coverslip and look under oil immersion
look for spores adhered to hair and for rotten log hairs (no definition)

Question 25

What is considered the gold standard for dermatophyte diagnosis

Answer 25

DTM culture
-difficult to interpret
can take 2-4 weeks for diagnosis
can speciate

Question 26

How does the Dermatophyte Test Media for culture work

Answer 26

1) Uses Sabourad’s Dextrose Agar (SDA) with phenol red that when dermatophyte eats the protein, the alkaline by-products increase the pH
this results in a red color change
but it will eventually turn red without dermatophytes

2) Dermatophyte growth must be white or “buff/fuzzy”
White/beige growth with color change

Check daily, store at room temp, protected from light

3) Can then speciate with Macroconidia (Macroconidia do not grow on the hosts) using a tape cytology from the culture plate

Question 27

After Dermatophyte culture what is used to speciate

Answer 27

Can then speciate with Macroconidia (Macroconidia do not grow on the hosts) using a tape cytology from the culture plate

Question 28

Macroconidia do not

Answer 28

do not grow on the host

(only on the culture plate)

Question 29

For dermatophytes,
systemic therapy kills ______
topical therapy prevents _____
environmental cleaning prevents _________

Answer 29

Systemics: kills infection
Topical: prevents spread
Environmental cleaning: prevents reinfection

Question 30

How long do you treat dermatophytes

Answer 30

until two consecutive negative cultures taken 1-2 weeks apart

Question 31

What is the dermatophyte treatment triad

Answer 31

Systemic therapy (every postive cat)
Topical therapy (every positive case, every exposed case)
Environmental cleaning

Question 32

You need to do systemic treatment for dermatophytes in

Answer 32

every positive cat

Question 33

How do you systemically treat cats with dermatophytes

Answer 33

Treat every cat
1) Itraconazole - concentrates well in skin/hair, pulse dosing
2) Terbinafine
3) possibly other -azoles but dont build in hair at good levels

Question 34

What anti-fungal do cats not tolerate

Answer 34

Ketoconazole

Question 35

What should you do for topical therapy in every animal that is postive and exposed to dermatophytes

Answer 35

Do at least twice weekly
1) Lime sulfur (gold standard)
-odor staining, difficult to apply
-must let it dry (e-collar)
-dont do in bathtub

2) Imidazoles (shampoo)- 10 min contact time
-Micronazole
-Clotrimazole
-Ketoconazole

Question 36

Why must you let lime sulfur dry with the animal wearing a cone

Answer 36

they will get diarrhea

Question 37

In dermatophyte cases, what should you do for environmental decontamination

Answer 37

-At least twice weekly, daily is better
-Vacuum thoroughly, shampoo carpets with beater brush, Swiffer for hard floors, wood oil soap for wood floors
-Wash bedding, clothes 2x on the longest cycle, hot water and bleach is not necessary
-Disinfect hard surfaces, remove all hair

Question 38

What should you do regarding dermatophytes and patient isolation

Answer 38

culture everybody
isolate positives to one treatment room (kittens need socialization)
gown up
get negatives out of there- treat topically if they must stay

Question 39

What is the most common equine dermatophytes

Answer 39

Trichopyton

Question 40

What should you do for Equine dermatophytosis

Answer 40

1) topical treatment
2) Twice- weekly bathing
-Imidazoles
-If suitably focal, could consider ointments/wipes BID

spontaneous remission is possible in 1-4 months