Pathogenic yeasts

Question 1

characteristics

Answer 1

-biocontainment level 2
-Candida=budding yeast; incubation of culture in serum for 2hrs leads to growth of germ tubes

-Cryptococcus- produces a large mucopolysaccharide capsule= antiphagocytic and immunosuppressive

-Malassezia- bottle shaped cells; first isolated from Rhino, fluoresces brick red under UV light

Question 2

Candida spp habitat

Answer 2

-common in environment and associated with hosts
-infections often caused by resident organisms

Question 3

Malassezia pachydermatis

Answer 3

-found on skin in mammals and birds
-localized to anatomical sites with lots of sebaceous glands= anus, ears, lips, interdigital skin

Question 4

Cryptococcus spp habitat

Answer 4

-C gattii= trees and soils

-C. neoformans= droppings of pigeons

-Radiotrophic, melanized C. neoformans- ID which are hypothesized to use ionizing radiation for energy

Question 5

Candida albicans in birds

Answer 5

-causes oral and crop candidiasis (infects mucous membranes where it normally lives; occurs when something out of balance) = crop thrush

-young birds most susceptible

-outbreaks of disease affecting large proportion of flock= sometimes seen as sequelae to coccidiostat treatment

-seen in variety of agricultural and pet bird species

Question 6

Candida albicans clinical signs in birds

Answer 6

-chicks don’t grow, listless, signs may be masked by predisposing disease

-gross lesions: raised, focal thickenings in mucosa of GIT

Question 7

Treatment of Candida albicans in birds

Answer 7

-Treat with in feed nystatin
-individual topical bird treatment
-May be linked with vit A deficiency (hypovitaminosis A= squamous metaplasia

Question 8

Control of candida albicans in birds

Answer 8

-management (diet, concurrent diseases)

-perhaps dipping of eggs in disinfectant

-segregate affected birds to protect against cannibalism

Question 9

candida albicans in horses

Answer 9

Thrush
-superficial infections of mucous membranes most common

-systemic candidiasis can also occur- opportunistic. Blood, resp tract, joints, urine

Question 10

Candida albicans in humans

Answer 10

3 syndromes:

1. Oropharyngeal
2. Genital/vulvovaginal
3. Invasive

Question 11

Oropharyngeal candida albicans

Answer 11

-white plaques on tongue
-rare in healthy adults, this is AIDS defining condition and seen in cancer

Question 12

Genital/vulvovaginal syndrome in candida albicans

Answer 12

Women- typically vulval pruritus, burning, discharge
-affects 75% of adult women at one point in life
-wear cotton underwear

Men- typically penile pruritic rash

Risks: pregnancy, diabetes, long term broad spectrum antimicrobials or corticosteroids

Question 13

Invasive syndrome of candida albicans in people

Answer 13

Candidemia increasingly encountered in bloodstream infection in hospitalized patients
-19-24% estimated mortality

Question 14

Malassezia pachydermatis in dogs

Answer 14

-causes superficial infections in warm, moist anatomic sites (interdigital skin, lips, ear canal, groin, skin folds)

-erythema, greasy exudate, malodorous exudate

-extensive lesions: lichenification, hyperpigmentation

-more common in warmer months

Question 15

Treatment of Malassezia pachydermatis

Answer 15

Topical therapy
-pyoderma= 2% miconazole, 2% chlorhexidine
-azole containing shampoos
-burrows solution for otitis externa

ID underlying disease
-atopy, food allergy, endocrinopathy

Question 16

Cryptococcus gattii in cats

Answer 16

-most common systemic mycosis of cats (8x as common in cats than dogs)

-emerging pathogen in Canada (trees and soil in Vancouver Island)

Question 17

Clinical signs of cryptococcus gattii in cats

Answer 17

1.Upper resp signs
-sneezing
-mucopurulent nasal discharge
-polyp like masses
-fluctuant subcutaneous swelling on bridge of nose

2. neurological signs
   -depression
   -changes in temperament
   -seizures
   -circling
   -head pressing
   -vestibular disease

Question 18

Cryptococcus gattii treatment

Answer 18

1.Azole antifungals= itraconazole, fluconazole, voriconazole all suitable options. Amphotericin B

2. surgical excision of large chunks of fungal infected tissues
3. Traumatic flushing
4. Long term follow up is important
   -can take up to 2 years
   -in FeLV/FIV positive cats, may need antifungals for life

Question 19

Cryptococcus in people clinical presentations

Answer 19

*Requires long term therapy, 6mths +

1. Lungs- pulmonary disease (cough, chest pain, fever)
2. CNS- cryptococcal meningitis (headache, fever, neck pain, nausea)

Question 20

C. neoformans vs. C. gattii in people

Answer 20

C. neoformans: often in pigeons. Common in People with pre existing conditions (AIDS, organ transplant, immunosuppressive therapy)

C. gattii: often affects healthy individuals

Question 21

Candida sample collection

Answer 21

-scrapings
-biopsies in formalin
-milk samples

Question 22

Malassezia sample collection

Answer 22

-cytological exam of exudates
-tape strip method
-biopsies

Question 23

Cryptococcus sample handling

Answer 23

-tissues for histopathology
-CSF
-lesions or exudates

Question 24

Candida lab ID

Answer 24

-colony appearance on culture
-microscopy

Question 25

Malassezia pachydermatis lab ID

Answer 25

-microscopy
-culture

Question 26

Cryptococcus lab ID

Answer 26

-microscopy of clear fluids
-india ink

Question 27

Cryptococcus neoformans as potential zoonoses

Answer 27

-not spread between individuals who are sick

-potentially a lab acquired infection, make sure to tell the lab you suspect this organism so that they can handle your samples safely

Question 28

Malassezia pachydermatis

Answer 28

-not a frequent human pathogen but possible

Question 29

Candida infections as a zoonoses?

Answer 29

No

Question 30

Treatment for Candida

Answer 30

-often topical
-Mystatin orally
-Azoles +/- amphotericin B

Question 31

Malassezia treatment

Answer 31

Topical
-shampoos/topical meds
-azoles

Question 32

Cryptococcus spp

Answer 32

Always systemic
-fluconazole; if it fails then itraconazole
-Amphotericin B