Derm1- SA Yeast Infections

  1. What is the most common etiologic agent that causes yeast dermatitis and otitis?
    Malassezia pachydermitis
  2. Where is Malassezia found in normal, healthy animals? (7)
    ear canal, anal sac, lips, chin, vagina, rectum, and skin [found in low numbers in healthy animals]
  3. What are pre-disposing factors for Malassezia yeast infections? (6)
    host defenses down, excess sebum problems, sebum quality (keratinization problems, allergies), moisture accumulation, disrupted epidermal surface, concurrent dermatoses
  4. What are predisposing diseases for Malassezia dermatitis? (6)
    allergies, keratinization disorders, bacterial skin diseases, metabolic diseases, endocrinopathies, cutaneous or internal neoplasia
  5. How does Malassezia cause inflammation and clinical signs?
    releases enzymes that alter sebum quality and disrupt the epidermal surface, may also activate complement--> inflammation and pruritus
  6. Describe the clinical presentation of Malassezia dermatitis. (3)
    moderate to intense pruritus, rancid odor, generalized or localized (ears, muzzle, interdigital areas, ventral neck, medial thigh, axillae, perianal region- all areas dense with sebaceous glands)
  7. What skin lesions are common with yeast dermatitis? (6)
    [all non-specific] erythema, scaling (greasy or dry) crusts, hyperpigmentation, lichenification, alopecia, red-brown discoloration
  8. What 3 localized Malassezia infections are most common in cats?
    paronychia (nail bed), chin acne, otitis externa
  9. What underlying conditions commonly predispose cats to generalized Malasseia dermatitis? (4)
    FIV/FeLV, neoplasia, diabetes, allergies
  10. How do you diagnose Malassezia dermatitis? (2)
    yeast identification via cytology (cotton swab smear, superficial skin scraping, acetate tape prep) is rather simple, culture/histo not usually necessary unless you suspect an underlying problem
  11. What method of sample collection is the most sensitive for identifying Malassezia?
    acetate tape preparation
  12. How do you treat yeast dermatitis? (3)
    identify and treat underlying cause, degreasing/antiseborrheic products, anti-fungal topical agents
  13. What antifungal agents are used with yeast dermatitis and what each is useful for? (4)
    • Sulphur/Salicylic acid: not good at degreasing, works for less oily cases
    • Benzoyl peroxide: degreasing, lacks antifungal component so must add that
    • Selenium sulfide: mild antifungal, very degreasing
    • Antifungal shampoos: with miconazole, climbazole, ketoconazle, chlorohexidine
  14. When is systemic therapy considered with yeast dermatitis?
    severe cases or when topical therapy is unsuccessful
  15. What systemic drugs have been efficacious at treating Malassezia dermatitis? (4)
    • Ketoconazole (severe side effects)
    • Itraconazole (fewer side effects, safer for cats)
    • Terbinafine (fewer drug interactions)
    • Fluconazole (?)
  16. What re-check protocol are important when managing Malassezia dermatitis? (4)
    re-check every 3-4weeks, cytology re-check, monitor serum liver enzymes if on systemic therapy, topicals can be used prophylactically
  17. In what circumstances is Malassezia zoonotic?
    immunocompromised individuals
  18. Image Upload 1
    Malassezia pachydermitis
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Derm1- SA Yeast Infections
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