36 – Pathogenic Yeasts Flashcards

1
Q

Microbiological characteristics: Candida

A
  • Budding yeast
  • Incubation of culture in serum for 2 hrs leads to growth of germ tubes
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2
Q

Microbiological characteristics: Cryptococcus

A
  • Produces large mucopolysaccharide capsule
    o Capsule is anti-phagocytic and immunosuppressive
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3
Q

Microbiological characteristics: Malassezia

A
  • *bottle shapped cells
  • M. pachydermatis: first isolated from Rhino with exfoliative dermatitis
  • M. furfur complex fluoresces brick red under UV light
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4
Q

Candida spp: natural host or habitat

A
  • Common in environment and associated with host
  • Infections often caused by resident organisms
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5
Q

Malassezia pachydermatis: natural host or habitat

A
  • Found on skin of mammals and birds
  • Localized to anatomical sites with lots of sebaceous glands
    o Anus, ears, lips, interdigital skin
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6
Q

Cryptococcus spp.: natural host or habitat

A
  • C. gatti: associated with trees and soil
  • C. neoformans: droppings of pigeons
  • Radiotropic, melanized C. neoformans ID which are hypothesized to utilize ionizing radiation for energy
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7
Q

What does Canadida albicans cause in birds?

A
  • Oral and crop candidiasis
  • *most commonly causes infections on the mucous membranes where it is normally found
  • *seen in variety of agricultural and pet bird species
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8
Q

What birds are most susceptible to Canadida albicans?

A
  • Young birds
  • *outbreaks of disease affecting large proportion of flock
    o Sometimes seen as sequelae to coccidiostat treatment (‘flock level procedure’)
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9
Q

What are the clinical signs of Canadida albicans?

A
  • Nonspecific
  • Chicks don’t grow, listless
    o Signs may be masked by predisposing disease
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10
Q

What are the gross lesions of Canadida albicans in birds?

A
  • Raised, focal thickenings in mucosa of GIT
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11
Q

How do you treat Canadida albicans in birds?

A
  • Possibly treating with in feed nystatin
  • Individual bird treatment (topical)
  • Possible association with vit A deficiency
    o Hypovitaminosis A leading to squamous metaplasia
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12
Q

How do you control Canadida albicans in birds?

A
  • Management (diet, concurrent disease, etc)
  • Perhaps: dipping eggs in disinfectant
  • Segregate affected birds to protect against cannibalism
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13
Q

What does Canadida albicans cause in horse?

A
  • Superficial infections most common
    o THRUSH: on mucous membranes
  • Systemic candidiasis: OPPORTUNISTIC
    o Blood, respiratory tract, joints, urine, etc.
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14
Q

What are the 3 syndromes recognized with Canadida albicans in humans?

A
  1. Oropharyngeal
  2. Genital/vulvovaginal
  3. Invasive
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15
Q

Oropharyngeal syndrome: Canadida albicans in humans

A
  • White plagues on tongue
  • Rare in healthy adults
    o AIDS defining condition
  • Also seen in people with cancer
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16
Q

Genital/vulvovaginal syndrome: Canadida albicans in humans

A
  • Women: vulval pruritus, burning, discharge
  • Men: penile pruritic rash
  • Wearing cotton underwear may reduce risk of infection
  • *affects 75% of all adult women at some point in their lifetime
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17
Q

What are the risks of genital/vulvovaginal syndrome: Canadida albicans in humans?

A
  • Pregnancy
  • Diabetes
  • Long-term broad spectrum antimicrobials or corticosteroids
18
Q

Invasive syndrome: Canadida albicans in humans

A
  • *candidemia=increasingly encountered bloodstream infection in hospitalized patients
  • Estimated: 25,000 cases annually in US (19-24% mortality)
19
Q

What does Malassezia pachydermatis cause in dogs?

A
  • Superficial infections in warm, moist anatomic sites
    o Interdigital skin
    o Lips
    o Ear canal
    o Groin
    o Skin folds
    o *erythema, greasy exudate, malodorous exudate
  • Extensive lesions
    o Lichenification (thickened areas of skin)
    o Hyperpigmentation
  • **more common in WARMER MONTHS
20
Q

How do you treat Malassezia pachydermatis in dogs?

A
  • Topical therapy is VERY IMPORTANT
    o Pyoderma: 2% miconazole, 2% chlorhexidine
    o Azole containing shampoos (Nizoral)
    o Burrow’s solution a very good choice for otitis externa
21
Q

What is crucial with Malassezia pachydermatis in dogs?

A
  • IDing and controlling underlying disease is CRITICAL
  • Ex. atopy, food allergy, endocrinopathy, etc.
22
Q

What does Cryptococcus gatti cause in cats?

A
  • Most common SYSTEMIC MYCOSIS in cats
    o 8x more common than in dogs
  • Emerged pathogen in Canada
23
Q

What is are the signs of Cryptococcus gatti in cats?

A
  • Upper respiratory signs
    o Sneezing
    o Polyp like masses
    o Fluctuant subcutaneous swelling on bridge of nose
  • Neurological signs possible
    o Depression, changes in temperament, seizures, circling, head pressing, vestibular disease
24
Q

What are Cryptococcus gatti and C. neoformans associated with worldwide?

A
  • C. gatti: TREES
  • C. neoformans: PIGEON FECES
25
Q

How do you treat Cryptococcus gatti in cats?

A
  • Azole antifungals
    o Itraconazole, fluconazole, voriconazole
  • Surgical excision of large chunks of fungal infected tissues
  • Traumatic flushing
26
Q

Long term follow up with cats that have/had Cryptococcus gatti

A
  • Long term therapy required
  • Can take up to 2 years
  • In FeLV/FIV positive cats=may need to treat with antifungals indefinitely
27
Q

Where does Cryptococcus spp. in humans often infect?

A
  • Lungs: cough, chest pain, fever
  • CNS=cryptococcal meningitis: headache, fever, neck pain, nausea
  • *requires long term therapy (6+ months)
28
Q

C. neoformans and people

A
  • Most commonly in people with PRE-existing conditions
    o AIDS, organ transplant, immunosuppressive therapy
29
Q

C. gatti and people

A
  • more likely to affect healthy individuals
  • not too common (6-24 cases on an annual basis)
30
Q

Candida: sample collection and handling

A
  • scrapings
  • biopsies in formalin
  • milk samples
31
Q

Malassezia: sample collection and handling

A
  • cytological examination of exudates
  • tape strip method
  • biopsies
32
Q

Cryptococcus: sample collection and handling

A
  • tissue for histopathology
  • cerebrospinal fluid
  • lesions or exudates
33
Q

Candida: Lab ID

A
  • colony appearance on culture
  • microscopy
34
Q

Malassezia pachydermatis: Lab ID

A
  • microscopy
  • culture
35
Q

Cryptococcus: lab ID

A
  • microscopy of clear fluids
  • India ink
36
Q

Candida: zoonotic/interspecies transmission

A
  • NOT considered zoonotic
37
Q

Malassezia pachydermatis: zoonotic/interspecies transmission

A
  • NOT a frequent human pathogen
    o Rarely reported in people, but don’t bring a therapy dog into a neonatal ICU
38
Q

Cryptococcus neoformans: zoonotic/interspecies transmission

A
  • NOT spread between individuals who are sick
  • Potentially a lab acquired infection
    o Make sure to tell the lab if you suspect it
39
Q

Canadida: treatment options

A
  • Often topical
  • Combination of topicals and systemic therapy
    o Nystatin orally
    o Azoles +/- amphotericin B
40
Q

Malassezia: treatment options

A
  • Often topical
  • Shampoos/topical medications
  • Azoles
41
Q

Cryptococcus spp.: treatment options

A
  • *always SYSTEMIC
  • Fluconazole: if fails then itraconazole
  • Amphotericine B