Yeast-like fungi

FUNGI

Candidosis

• Caused by Candida spp.
• Noramlly present on skin and in GI tract
• Immunocompromised animals may show symptoms
• Usually lesions on mucous membranes and at mucocutaneous junctions
• Grossly:
  • Exudative, papular, pustular to ulcerative dermatitis
  • Stomatitis and otitis externa may develop
• Microscopically:
  • Spongiotic neutrophilic pustular inflammation
  • Parakeratosis
  • Ulcerations
  • Superficial exudate containing organisms

Malassezia pachydermidis

• Caused by Malassezia pachydermatis

• Normally present in oily areas on the external ear canal and skin in dogs
  • Some strains have been recovered from the ear canal of cats

• Bottle-shaped, small budding cells, non-mycelial

• Gram stain shows purple yeast cells with a very wide base

• Grow on Sabouraud's Dextrose agar in 2 weeks of incubation at room temperature

• Greenish discolouration on blood agar

• Clinical disease may cause yeast to proliferate and cause infection
• Grossly:
  • Regional lesions: muzzle, ears, interdigital, perianal
  • Or generalised disease
  • Erythematous, hyperpigmented, lichenified and scaly lesions with alopecia
• Microscopically:
  • hyperkeratosis, parakeratosis
  • Spongiotic pustular dermatitis
  • Acanthosis
  • Organisms are usually present, minimum 3-5 yeasts per high-power field must be found to imply cause of disease

Rhodotorula

• Rhodotorula minuta and R. rubra

• Canine ear infections

• Equine uterus

• Seldom seen in animal infections

Torulopsis glabrata

• Commensal in animals and is found in the soil

• Implicated in cases of:
  • Pyelonephritis, pneumonia, septicaemia and meningitis (humans)
  • Mastitis and abortion in cattle
  • Systemic infection of monkeys and dogs

Trichosporonosis

• Found in soil

• Deuteromycetes yeast

• Trichosporonosis beigelii
  • Implicated in feline nasal granuloma, skin infections in horses and monkeys, mastitis in cattle and sheep and in feline bladder infections

• T. capitum implicated in bovine mastitis

Further Links

• Mycotic skin infections - Pathology

• Cryptococcus neoformans causes granulomatous rhinitis in cats, see respiratory infections
• Candida is an opportunistic pathogen at mucus membranes, causing thrush.
• Blastomyces dermatitidis in blastomycosis in lungs
• Histoplasma capsulatum in histoplasmosis in lungs
• Candida spp. in candidiasis
• Malassezia pachydermis in malassezia dermatitis