Dermatophytosis

Question 1

Define dermatophytosis

Answer 1

Superficial fungal infections

Question 2

Pathogenesis of Dermatophytosis

Answer 2

• invasion of non-viable, keratinized tissue
• Production of metabolic by-products and toxins
  
  • inflammation, and Hypersensitivity reactions
• Secondary folliculitis and furunculosis
• Severe infections may be seen in immunocompromised host
  
  • Glucocorticoid therapy

Question 3

Ectothrix

Answer 3

Spores that are produced on the outside of the hair

Question 4

Endothrix

Answer 4

Spored that are produced inside the hair

Question 5

Clinical features of dermatophytosis

Answer 5

Circular alopecic areas, erythema, crusts, scale, hyperpigmentation, nodules, pustules

May see brittle or broken hairs

Mild to moderate pruritus

Question 6

What is the most common dermatophyte found in Iowa

Answer 6

Microsporum canis

Question 7

What are common dermatophytes of cats and dogs?

Answer 7

• Microsporum canis*
• Microsporum gypseum*
• Trichophyton mentagrophytes*

Question 8

What are methods of diagnosis of dermatophytes?

Answer 8

clinical features

Wood’s lamp examination

Trichogram/KOH preparation

Fungal culture with microscopic identification

Fungal PCR

Skin biopsy

Question 9

What are the treatment objectives for dermatophytosis cases

Answer 9

Shorten course of infection and reduce severity of lesions/discomfort

Reduce dissemination of infective materials (hair/scale) into the environment

Question 10

Dermatophyte decontamination of a pet

Answer 10

• Total Body Clip
  
  • Reduces infectivity
  • speeds recovery
  • danger of environmental contamination
  • clip carefully to avoid trauma using #10 blade

Question 11

topical dermatophyte therapy

Answer 11

not recommended as a sole treatment.

May disperse spores

Consider topical lotions/creams for focal lesions as adjunctive treatment

Bathe weekly as concurrent therapy

Question 12

what are systemic therapy options for dermatophytosis

Answer 12

• Griseofulvin
• Azoles
  
  • Ketoconazole
  • Itraconazole
  • Fluconazole
• Lufenuron
• Terbinafine

Question 13

Griseofulvin

Answer 13

Fungistatic systemic therapy used against dermatophytosis infections.

This is a teratogen - don’t use in pregnant animals

Treatment duration: 4-8 weeks

Better products on the market such as the Azoles

Question 14

Ketoconazole

Answer 14

inhibits p-glycoprotein efflux pump

Best given with a meal to increase absorption

Question 15

Itraconazole

Answer 15

Inhibits ergosterol synthesis: fungistatic

Should be avoidedin pregnant animals

Considered the BEST AZOLE for Dermatophytes

Most expensive azole

Question 16

Is Itroconazole equivilent for compounded itraconazole

Answer 16

No it is not

Generic itraconazole may be effective at higher dosages

Question 17

Fluconazole

Answer 17

Similar to itraconazole

excellent penetration into CSF, eye, claws

Adverse effects: increased hepatic enzymes, not given in pregnancy

Question 18

Terbinafine

Answer 18

Fungicidal: inhibits squalene eposidase necessary for ergosterol synthesis.

Relatively few side effects

Question 19

Decontamination of the environment from Dermatophytes

Answer 19

Launder bedding, carpet

change furnace filters, heating ducts in homes

Vacuum and dispose

Disinfectant sprays/cleansers in appropriate areas (dog houses etc)

Question 20

What are methods of monitoring a dermatophyte case

Answer 20

Clinical signs such as hair growth

Trichogram

Fungal culture

Recommended 4 weeks of therapy beyond “clinical” cure.

Question 21

Are dermatophytes zoonotic?

Answer 21

yes.

Human infections are common

Children may have close contact with kittens and puppies

Lesions can be painful

Therapy can be expensive and long

Question 22

What are risk factors to humans for dermatophytes

Answer 22

adoption from humane society/shelters

Exposure to large numbers of animals, groomers, veterinarians, shelter workers

immunosuppression

Question 23

When should you use a Lime Sulfur rinse for a dermatophyte case?

Answer 23

Utilize this on day 1 to decrease the presence of pruritus.

Question 24

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