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Bacteriology 2 > 5.14 Mycology > Flashcards

5.14 Mycology Flashcards

1
Q

How are fungi classified?

A

mold, yeast, dimorphic

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2
Q

nature of mold

A

arial mycelia and vegetative mycelia present at both environmental and body temp

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3
Q

yeast nature

A

bacterial-like growth at both environmental and body temp

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4
Q

nature of dimorphic fungi

A

mold-like growth at environmental temp and bacterial-like growth at body temp

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5
Q

broad types of mycotic infection sin animals

A

superficial, subcutaneous, systemic

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6
Q

types of superifcila mycoses that i have to know

A

dermatophytes
malassezia pachydermatis

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7
Q

what is ringworm? where does it infect the body? what type of infections? what species? zoonotic?

A

ringworm is a superficial mycoses; dermatophyte
* Fungal parasites of keratinized epithelium of skin, hairs and nails
* Non-invasive, superficial infections (don’t grow at 37C)
* Many species partially host-adapted (anthropophilic, zoophilic)
* Zoonotic

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8
Q

what are the organisms that cause ringowm

A

a variety cause ringworm in different species;

Trichophyton:
>T. verrucosum; Cattle
>T. mentagrophytes; Broad host range
>T. equinum; Horse

Microsporum:
>M. canis; Cat, Dog
>M. nanum; Pig
>M. gypseum; Dogs

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9
Q

Classic ringworm lesion

A

Slowly expanding, circular area alopecia and desquamated epithelium (“cigarette ash”). Central hair regrowth, inflamed edge. Often multiple differently sized lesions

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10
Q

Ringworm: treatment

A
  • Topical treatments (azoles, disinfectants)
  • Parenteral: Griseofulvin, itraconazole, ketoconazole
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11
Q

Ringworm: control

A
  • Hygiene: Isolation; treatment bedding with formalin
    or washing in bleach; decontaminate environment
  • Vaccines for cats and cattle
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12
Q

Malassezia pachydermatis; what is it? what does it look like? where is it commonly found and what diseases does it cause?

A

Superficial mycoses:
Malassezia pachydermatis
* Pear-shaped or “footprint” shaped yeast, 3-8μm
* Common in dog’s ears, skin
* May cause otitis externa in dogs (excess wax in ears?), increasingly recognized as a cause of dermatitis

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13
Q

main subcutaneous mycoses that we have to know

A

Sporothrix schenkii

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14
Q

what is Sporothrix schenkii? what disease does it cause and in what animals? where is it found geographocally and what is its habitat? what tissues does it infect?

A

Subcutaneous mycoses:
Sporothrix schenkii
(Rose gardener’s disease)
* Sporotrichosis in horses, dogs, cats and humans
* Worldwide, more common in tropical/subtropical regions
* Habitat: rose thorns, soil, dead vegetation
* Subcutaneous nodules, lymphatics (rare lungs)

Sporothrix schenkii is a dimorphic fungi

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15
Q

what kind of fungi is Sporothrix schenkii?

A

dimorphic
“Mold in the Cold, Yeast in the Heat”
mold at 25C
yeast at 37C

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16
Q

what systemic mycoses do i have to know

A

Cryptococcus
>neoformans
>gatti

Blastomyces dermatitidis

Histoplasma capsulatum

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17
Q

agents of cryptococcosis?

A
  • Cryptococcus neoformans and Cryptococcus gattii are the agents of cryptococcosis
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18
Q

what is Cryptococcus? what species are we concerned with and what do they cause? what type of fungi are they? what is their structure?

A

Systemic mycoses: Cryptococcus
* Cryptococcus neoformans and Cryptococcus
gattii are the agents of cryptococcosis
* Dimorphic fungi: yeast in vivo, encapsulated,
fast growing

19
Q

C. neoformans; where is it found, who does it infect?

A

Bird manure especially pigeons, worldwide, disease of immunocompromised

20
Q

C. gattii; where is it found, who does it infect?

A

More virulent; associated plant debris, esp. eucalyptus, affects healthy animals and people (West Coast, BC)

21
Q

which is more virulent; C. neoformans or C. gatti?

A

C. gatti

22
Q

Cryptococcus; what infections and lesions does it cause? in what species?

A
  • Respiratory infection
  • Skin lesions
  • Neurological disease
  • Cats+++, dogs, cattle, horses, sheep, goats, birds

“clown nose in cats”

23
Q

Cryptococcus can cause what unique disease in cats?

A

clown nose

24
Q

Blastomyces dermatitidis; what type of fungus is it?

A

Systemic mycoses: Blastomyces dermatitidis
dimorphic
“Mold in the Cold, Yeast in the Heat”

25
Q

Blastomyces dermatitidis physical character

A

“Mold in the Cold, Yeast in the Heat”
Mycelium at 25C: Hyphae with “pear-shaped” conidia
Yeast at 37C ”thick walls”

26
Q

Blastomyces dermatitidis; where is it found geographically? who is susceptible?

A
  • Blastomyces dermatitidis
  • Acidic soil and organic material
  • Distribution appears to be growing
  • Also occurs in Europe, Asia and Africa
  • Dogs are 10x more susceptible to blastomycosis than humans
  • Occasionally affect other mammals
27
Q

Blastomyces dermatitidis lesions

A

Primary lesions in lungs with metastases to skin and other organs

28
Q

Blastomyces dermatitidis: transmission and pathogenesis

A

mold form survives in organic materials or acidic soils
-conidia are inhlanes by dog or humans

> Dimorphic change to yeast form in lung of host
Yeast are very resistant to killing by leukocytes => pneumonia
Immunosuppression (e.g., lymphopenia) may promote dissemination to skin, bone, lymph nodes, eye or other organs

29
Q

Canine blastomycosis lesions in dog

A

Diffuse interstitial nodular pneumonia

Eye lesions (e.g., uveitis) are present in up to 40% of cases

Cross-section of infected lung - note the massive influx of inflammatory cells and how little oxygen could be transported in this lung

Skin lesions (e.g., onchyomycosis – B. dermatitidis infection of toe nail)

B. dermatitidis ulcerative dermatitis near face - may be seen in 20-50% of cases

B. dermatitidis ulcerations on planum nasale

30
Q

Blastomycosis in humans; type of disease, transmission, lesions, treatment and prognosis

A
  • Respiratory disease usually apparent
  • It cannot be spread among humans and dogs
  • Skin granulomas are seen (chronic inflammation)
  • May be confused with skin cancer
  • Need to diagnose and aggressively treat
  • Can be fatal if left untreated
31
Q

Histoplasma capsulatum; what is it? what type of fungi?

A

Systemic mycoses:
Histoplasma capsulatum
“Mold in the Cold, Yeast in the Heat”
mold: Hyphae and macroconidia/microconidia

32
Q

Histoplasma capsulatum; what species infected? zoonotic? carriers?

A
  • Dogs, cats and humans (zoonotic!!!)
  • Organism does not infect birds, but they are carriers!
  • Bats can contract histoplasmosis and spread disease
33
Q

Histoplasma capsulatum lesions?

A
  • Primary lesions in lungs with dissemination to intestines and other organs
34
Q

Histoplasmosis is found where geographically?

A

is endemic in Mississippi and Ohio River valleys and some tropical areas

35
Q

Histoplasma capsulatum: transmission/ pathogenesis

A

H. capsulatum mold form lives in top layer of soil
containing infected bird or bat guano

> Microconidia are released and are inhaled by animals, humans
Microconidia convert to yeast form in the lung of an animal and infect alveolar macrophages
H. capsulatum inside macrophages disseminates throughout the body

36
Q

Histoplasmosis in dogs; what disease? what clinical signs? what about cats?

A

Histoplasmosis in dogs
Respiratory disease
* Clinical signs often mild, if apparent at all
* Serious respiratory disease only in a small percent of dogs
* H. capsulatum disseminates to other tissues in dogs

> could see emaciation due to malabsoption form histoplasma capsulatum enteritis
could see enlarged mesenteric lymph nodes in dog with disseminated histoplasmosis

  • Cats are also highly susceptible
37
Q

Coccidioides immitis; what type of fungi

A

“Mold in the Cold, Yeast in the Heat”
dimorphic

38
Q

Coccidioides immitis found in what species? primary lesions?

A
  • Dogs, horses, cats, humans
  • Primary lesions in lungs and secondary in bones
39
Q

Coccidioides immitis found where geographically?

A
  • Endemic areas
  • New Mexico, Texas, California, Arizona
  • Known as “Valley fever”
  • Northern Mexico, Central America, Argentina
40
Q

Coccidioides immitis ecology

A
  • soil of low elevation, deserts
  • Hot summers, cold winters
41
Q

Coccidioidomycosis - Life Cycle

A

Mold form
* Hyphae fragment to form arthroconidia which become airborne and inhaled
* As few as 10 inhaled arthroconidia can produce disease

“Yeast-like form
* Arthroconidia transform into spherules inside the lung of host

NO YEAST FORMATION! IT IS A SPHERULE!

spherules mature and rupture, releaseing many small apherules in host

42
Q

Coccidioidomycosis - Canine symptoms

A

Coccidioidomycosis - Canine
Most dogs are asymptomatic (95%) Some show signs of pneumonia
* High Fever
* Lethargy, inappetence
* Dry, harsh cough
> May be confused with kennel cough
(B. bronchiseptica)

Pneumonia may lead to dissemination! (5% of cases)
– Osteomyelitis

43
Q

what type os fungus lead to systemic infections with primary lesions in lungs?

A

blastomyces (dimorphic)
coccidiodes (mold and SPHERULE)
histoplasma (dimorphic)

44
Q

what type of fungus leads to subcutaneous and lymphatic lesions?

A

sporothrix

Bacteriology 2 (10 decks)

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