Yeasts

Structure

Unicellular, round or oval organisms

What kind of reproduction

Asexual reproduction by budding

Produces blastoconidia

Blastoconidia can bud from

a - mother cell, b - hyphae, c - pseudohyphae

What are the names of genera 

Candida albicans, Cryptococcus neoformans, Malassezia pachydermatis

Cultures of all

SDA aerobically 37

Candida albicans are ___morphic

Polymorphic (pseudohyphae, true septate hyphae and budding yeast cells)

What are the main virulence factors of candida albicans

Biofilm (make resistant to antifungals and immune system)

Phenotypic switching to adapt to host environment 

What does candida albicans cause in dogs, cats, cows and horses

Dogs - enteritis, cutaneous lesions, mycotic stomatitis

Cats - cystitis, pyothorax, ocular lesions

Cows - abortions, mastitis, gastroesophageal ulcers, rumenitis 

Horses - ulcers, pyometra, ocular lesions

What does candida albicans overall affect

Oral cavity, GI tract, urogenital tract

Microscopy candida albicans

See polymorphy

Cryptococcus neoformans shape

Round to oval cells

Daughter call are formed as bud 

What is the main virulence factor of cryptococcus neoformans

Capsule → inhibit phagocytosis and suppressed immune response

Phenol oxidase —> accumulation of melanin for protection 

What is the name of the condition caused by cryptococcus neoformans

Cryptococcosis

What does cryptococcosis cause in cats, dogs, cattle,horses

Cats - nasal swelling, sneezing, CNS signs (seizures, depression)

Dogs - ocular disease, CNS involvement

Cattle - mastitis and nasal granulomas 

Horses - nasal granulomas, sinusitis, cutaneous lesions, pneumonia, abortion

Microscopy cryptococcus neoformans

Mucoid colonies, presence of capsules

Malassezia morphology

Bottle shaped, thick walled, monopolar budding

What does malassezia release

Lipase which alters oils, leading to irritation and inflammation 

Can cause excessive ear wax and tissue damage in ears 

What does malassezia pachydermatis cause in cats and dogs

Dogs - otitis externa (head shaking, discharge, inflammation), seborrheic dermatitis (greasy coast and foul odor)

Cats - feline chin acne, dermatitis

Microscopy malassezia pachydermatis

Use of methyl bue and gram stain to see yeast cells