Dermatology - Malassezia Dermatitis Flashcards
Describe Malassezia pachydermatis (i.e what type of fungi and where it lives).
It is a non-obligatory, lipophilic, budding yeast considered part of the normal flora of the skin and external ear canal
Malassezia infections are almost always _____ _____.
secondary conditions - perpetuating factors of pruritus
What are the typical underlying causes associated with Malassezia infections?
atopy, other allergic skin diseases, endocrine imbalances, systemic illness, immunodeficiency syndromes, including glucocorticoid administration, nutritional deficiencies
What are predisposing factors to Malassezia infections?
breed, presence of seborrheic dermatitis, increased temperature, increased humidity, and immunodeficiency conditions
What is the pathogenesis of Malassezia infections?
- Activation of the alternate pathway of complement
- Production of enzymes and toxins that induce inflammation
- Hypersensitivity reactions
- Synergistic actions with Staph. Pseudintermedius
What breeds are predisposed to Malassezia infections?
Chinese shar-pei, basset hound, american cocker spaniel, boxer, dachshund, and labrador retriever
What is the main historical feature associated with Malassezia infections?
intense pruritus
What other historical features are associated with Malassezia infections?
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
What physical findings are associated with Malassezia infections in the exam room?
Intense pruritus, scratching and biting in the exam room
How do lesions appear in cases of Malassezia infections?
They begin as erythema and scaling, then progress to alopecia, lichenification, and hyperpigmentation
What does the skin and hair coat look like in patients with Malassezia infections?
it appears greasy and malodorous
What clinical condition, aside from the intense pruritus is commonly seen in patients that have Malassezia infections?
otitis externa
How do the peripheral lymph nodes present in patients with Malassezia infections?
they are enlarged and prominent
When diagnosing Malassezia infections, what should be done first?
You need to identify the primary factor
What are the recommended diagnostic procedures for identifying the primary factor in Malassezia cases?
history, PE, dermatology data base, allergy tests, tests to evaluate for endocrine disease, routine hematology
How are yeast infections confirmed?
Impression smears of affected skin, using adhesive tape, clean glass microscope slides, or slides with adhesive
What is a 0 on Dr. Noxon’s subjective Malassezia scale?
no yeast on slide
What is a 1 on Dr. Noxon’s subjective Malassezia scale?
few yeast on slide (1-4)
What is a 2 on Dr. Noxon’s subjective Malassezia scale?
several yeast on slide (5-12)
What is a 3 on Dr. Noxon’s subjective Malassezia scale?
one organism seen every 2-4 high dry or oil immersion fields
What is a 4 on Dr. Noxon’s subjective Malassezia scale?
one or more yeast found per microscope field
What grade on the scale warrants therapy?
a 2+ or greater
In patients with Malassezia infections, what will a skin biopsy show?
hyperplastic dermatitis, with orthokeratotic hyperkeratosis, superficial perivascular dermatitis, with varying degrees of crusts
How is Malassezia managed (generally)?
control concurrent bacterial dermatitis, treat the yeast infection, identify and control the preliminary disease
What treatments can be used to treat Malassezia infections?
Systemic antifungals, shampoos, and some other topical treatments
Can shampoos be used as the sole treatment for Malassezia infections?
yes, but they can also be used in conjunction with systemic therapy
Selsun Blue, the human dandruff shampoo can be used to treat Malassezia infections, what effective ingredient is in it?
selenium disulfide
What effective ingredients are in Nizoral or KetoChlor shampoos?
salicylic acid and ketoconazole
What effective ingredient is in Dermazole, miconazole Shampoo, or MalaSeb shampoos?
miconazol
What effective ingredient is in Hexidien shampoo?
chlorhexidine
What is the recommended protocol for using shampoos in treatment of Malassezia infections?
- Bathe 1-3 times weekly for three weeks, depending on other treatments
- For maintenance, continue bathing as needed (every 1-2 weeks) until (if) the primary disease is identified and controlled
When can shampoos be used as the primary treatment of Malassezia dermatitis infections?
If, and only if, the owners are conscientious in the application of the shampoo
What ‘other’ topical therapies can be used to treat Malassezia infections?
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
What is the recommended protocol for using sprays in treatment for Malassezia infections?
Recommended daily in the trouble spots for 10-14 days and then every 1-4 days for maintenance or preventative use
What systemic antifungals are recommended for Malassezia infections?
Ketoconazole (or itraconazole or fluconazole)
What is the recommened protocol for using ketoconazole in treatment of Malassezia infections?
5 mg/kg PO SID with food for 30 days
What adverse effects are associated with use of ketoconazole?
increased liver enzymes, anorexia (cats), and alopecia
What drug is recommended for cats?
Itraconazole or fluconazole
What is the recommended protocol for using Itraconazole in treatment of Malassezia infections?
5 mg/kg on two consecutive days/week for long term control
What is the fluconazole dosage used for yeast?
5 mg/kg PO SID for 30 days
When should re-examinations be performed?
after 30 days of treatment
What is important to stress to your clients when treating Malassezia infections?
the primary disease must be identified and controlled for long-term success of treatment
What is the standard treatment for most dogs with yeast infections?
- Bathe 1-2 times weekly for 2-3 weeks
- Use wipes or pads 1-2 times daily to treat troublesome locations or for most severe locations
- 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
