Dermatology - Malassezia Dermatitis Flashcards

1
Q

Describe Malassezia pachydermatis (i.e what type of fungi and where it lives).

A

It is a non-obligatory, lipophilic, budding yeast considered part of the normal flora of the skin and external ear canal

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2
Q

Malassezia infections are almost always _____ _____.

A

secondary conditions - perpetuating factors of pruritus

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3
Q

What are the typical underlying causes associated with Malassezia infections?

A

atopy, other allergic skin diseases, endocrine imbalances, systemic illness, immunodeficiency syndromes, including glucocorticoid administration, nutritional deficiencies

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4
Q

What are predisposing factors to Malassezia infections?

A

breed, presence of seborrheic dermatitis, increased temperature, increased humidity, and immunodeficiency conditions

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5
Q

What is the pathogenesis of Malassezia infections?

A
  1. Activation of the alternate pathway of complement
  2. Production of enzymes and toxins that induce inflammation
  3. Hypersensitivity reactions
  4. Synergistic actions with Staph. Pseudintermedius
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6
Q

What breeds are predisposed to Malassezia infections?

A

Chinese shar-pei, basset hound, american cocker spaniel, boxer, dachshund, and labrador retriever

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7
Q

What is the main historical feature associated with Malassezia infections?

A

intense pruritus

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8
Q

What other historical features are associated with Malassezia infections?

A

History of licking feet, rubbing face, generalized pruritus that initially responded to glucocorticoid therapy, but then becomes less and less responsive - they appear to be an atopy case of of control

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9
Q

What physical findings are associated with Malassezia infections in the exam room?

A

Intense pruritus, scratching and biting in the exam room

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10
Q

How do lesions appear in cases of Malassezia infections?

A

They begin as erythema and scaling, then progress to alopecia, lichenification, and hyperpigmentation

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11
Q

What does the skin and hair coat look like in patients with Malassezia infections?

A

it appears greasy and malodorous

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12
Q

What clinical condition, aside from the intense pruritus is commonly seen in patients that have Malassezia infections?

A

otitis externa

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13
Q

How do the peripheral lymph nodes present in patients with Malassezia infections?

A

they are enlarged and prominent

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14
Q

When diagnosing Malassezia infections, what should be done first?

A

You need to identify the primary factor

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15
Q

What are the recommended diagnostic procedures for identifying the primary factor in Malassezia cases?

A

history, PE, dermatology data base, allergy tests, tests to evaluate for endocrine disease, routine hematology

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16
Q

How are yeast infections confirmed?

A

Impression smears of affected skin, using adhesive tape, clean glass microscope slides, or slides with adhesive

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17
Q

What is a 0 on Dr. Noxon’s subjective Malassezia scale?

A

no yeast on slide

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18
Q

What is a 1 on Dr. Noxon’s subjective Malassezia scale?

A

few yeast on slide (1-4)

19
Q

What is a 2 on Dr. Noxon’s subjective Malassezia scale?

A

several yeast on slide (5-12)

20
Q

What is a 3 on Dr. Noxon’s subjective Malassezia scale?

A

one organism seen every 2-4 high dry or oil immersion fields

21
Q

What is a 4 on Dr. Noxon’s subjective Malassezia scale?

A

one or more yeast found per microscope field

22
Q

What grade on the scale warrants therapy?

A

a 2+ or greater

23
Q

In patients with Malassezia infections, what will a skin biopsy show?

A

hyperplastic dermatitis, with orthokeratotic hyperkeratosis, superficial perivascular dermatitis, with varying degrees of crusts

24
Q

How is Malassezia managed (generally)?

A

control concurrent bacterial dermatitis, treat the yeast infection, identify and control the preliminary disease

25
Q

What treatments can be used to treat Malassezia infections?

A

Systemic antifungals, shampoos, and some other topical treatments

26
Q

Can shampoos be used as the sole treatment for Malassezia infections?

A

yes, but they can also be used in conjunction with systemic therapy

27
Q

Selsun Blue, the human dandruff shampoo can be used to treat Malassezia infections, what effective ingredient is in it?

A

selenium disulfide

28
Q

What effective ingredients are in Nizoral or KetoChlor shampoos?

A

salicylic acid and ketoconazole

29
Q

What effective ingredient is in Dermazole, miconazole Shampoo, or MalaSeb shampoos?

A

miconazol

30
Q

What effective ingredient is in Hexidien shampoo?

A

chlorhexidine

31
Q

What is the recommended protocol for using shampoos in treatment of Malassezia infections?

A
  1. Bathe 1-3 times weekly for three weeks, depending on other treatments
  2. For maintenance, continue bathing as needed (every 1-2 weeks) until (if) the primary disease is identified and controlled
32
Q

When can shampoos be used as the primary treatment of Malassezia dermatitis infections?

A

If, and only if, the owners are conscientious in the application of the shampoo

33
Q

What ‘other’ topical therapies can be used to treat Malassezia infections?

A

rinses: acetic acid and vinegar (Dechra/DermaPet) or 2% lime sulfur
Sprays: Malaseb rinse, Malacetic Ultra, MalaKet spray
Wipes/pads: Malacetic wipes, MalaKet wipes, Malseb Pledgets

34
Q

What is the recommended protocol for using sprays in treatment for Malassezia infections?

A

Recommended daily in the trouble spots for 10-14 days and then every 1-4 days for maintenance or preventative use

35
Q

What systemic antifungals are recommended for Malassezia infections?

A

Ketoconazole (or itraconazole or fluconazole)

36
Q

What is the recommened protocol for using ketoconazole in treatment of Malassezia infections?

A

5 mg/kg PO SID with food for 30 days

37
Q

What adverse effects are associated with use of ketoconazole?

A

increased liver enzymes, anorexia (cats), and alopecia

38
Q

What drug is recommended for cats?

A

Itraconazole or fluconazole

39
Q

What is the recommended protocol for using Itraconazole in treatment of Malassezia infections?

A

5 mg/kg on two consecutive days/week for long term control

40
Q

What is the fluconazole dosage used for yeast?

A

5 mg/kg PO SID for 30 days

41
Q

When should re-examinations be performed?

A

after 30 days of treatment

42
Q

What is important to stress to your clients when treating Malassezia infections?

A

the primary disease must be identified and controlled for long-term success of treatment

43
Q

What is the standard treatment for most dogs with yeast infections?

A
  1. Bathe 1-2 times weekly for 2-3 weeks
  2. Use wipes or pads 1-2 times daily to treat troublesome locations or for most severe locations
  3. After 2-3 weeks, bathing may continue weekly if needed, or reduced to every 7-14 days. Topical wipes should continue on trouple spots every 2-7 days