Fungal Jungle!

Question 1

What is fungus?

Answer 1

• It can be parasitic or free-living in the environment.
• Most are multi-cellular (except yeasts)

Question 2

Mycology

Answer 2

The study of fungi

Question 3

Identifying fungi (4)

Answer 3

1. Description growth
2. Description of color
3. Description of sexual spores
4. Description of asexual spores

Question 4

Hyphae
Hint: Fairy tree

Answer 4

Filament or branch from which the fungus grows.

(Hyphae tips can grow either from mitosis or meiosis depending on the type of fungus)

Question 5

Mycelium
Hint: Big fairy tree

Answer 5

The intertwined mass of hyphae that forms the mold colony

Question 6

Arthrospores

Answer 6

• Asexual
• Thick walled spores formed by hyphal septation.
• Are able to survive harsh conditions.

Question 7

Conidia
Hint: Outside the fairy tree

Answer 7

Asexual spores borne externally on hyphae (branches)

Question 8

Yeast
Hint: “Hey buddie”

Answer 8

• No hyphae
• Multiply by budding

Question 9

Pathogenic Fungi Groups: Fungi Imperfecta (4)

Answer 9

Important species include:
- Dermatopytes: Microsporum & Trichophyton.
- Histoplasma
- Candida
- Aspergillus

Question 10

Aspergillus
Hint: Common throughout the world

Answer 10

• Usually causes disease in birds, but can for any species.
• Germ. Shep. are at high risk.

Symptoms:
- Severe nasal & sinus infections.
- Can cause pneumonia
- Very difficult to treat

Question 11

Dermatophytes
Hint: “ringworm”

Answer 11

• Keratinophilic fungi that invade hair, nails, & superficial skin layers.
• Lesions are pruritic & cause crusty skin and hair loss.
• Different presentations in diff. species.
• Often contagious and spores are hard to kill!

Question 12

What are the 4 pathogenic fungi groups?

Answer 12

1. Mushrooms
2. Cup fungi
3. Molds
4. Fungi imperfecti - no sexual stage

Question 13

Dermatophytes - How the fungi disease invades (3)

Answer 13

• Fungi enter hair follicles by growing down hair shafts (gets into the shaft).
• Invades keratin (toughest layer of the skin).
• Arthospores form as hair grows upward.

Question 14

How to diagnose dermatophytes? (3)

Answer 14

1. Woods black lamp.
   - Florescent hyphae in hair shafts.
   - Only some strains of fungus will be (+)!!!
2. Direct Microscope Eval.
   - KOH prep
   - Consists of prep of specimen using Potassium “P” Hydroxide “OH”
3. Dermatophytes Test Medium.
   - “DTM”

Question 15

How do you preform a KOH prep?

Answer 15

1. Arthrospores grow on the outside of the hair shaft but cannot normally be seen.
2. Pluck a few hairs from the PERIHERY of the lesion (not on!).
3. Place on slide w/1-2 drops of 10% KOH & add cover slip.
4. Warm for 2-10min.
5. Arthrospores visible along a hair shaft.

Question 16

Dermatophyte Test Medium (DTM)
Medium: (4)
Type of test?
How does it work?
Reliability?
How to prep?

Answer 16

1. Selective & differential
2. Only grows fungi & has red color change in 7d.
3. Most reliable test.
4. Area/lesion should be cleaned with alc. then hairs plucked from the EDGE of the lesion.

Question 17

Mushrooms:
What is their importance?
What are the causes if exposed? (4)

Answer 17

1. Medically important due to toxicity of ingestion.
2. If ingested, it can cause: vomiting/diarrhea, neurologic signs, liver/kidney failure, & death.

Question 18

Who is at risk of dermatophytes as a zoonotic disease?

Answer 18

1. Children
2. Damaged skin
3. Animals (esp cats!) can be asymptomatic carriers.

Question 19

Yeasts: Malassezia
Species of yeast?
Where is it likely to occur on a patient?

Hint: this is a common cause of dermatitis

Answer 19

1. Species of lipophilic yeast.
2. Skin folds, ears of allergic dogs

Question 20

Malassezia (yeast) diagnosis:
Tape prep (3)

Answer 20

1. Using a small strip of transparent tape, lay it on the skin lesion and press lightly.
2. Apply a drop of blue from Diff-Quik stain set.
3. Lay sample side down on the slide.

Question 21

Malassezia (yeast) diagnosis:
Direct smear (6)

Answer 21

1. Moisten a sterile swab w/sterile saline.
2. Swab area of interest (skin lesion, vagina, ear).
3. Roll swab gently onto a microscope slide.
4. After airdrying, heat fix using gram stain.
5. Stain w/Gram Stain or Dif Quik.
6. Observe!

Question 22

Therapy for Malassezia (3)

Answer 22

1. Anti-fungal agents
2. Treat bacterial infections if present.
3. Treat underlying cause (allergies, skin care, surgery)

Question 23

What dog breeds are especially at risk for Malassezia (yeast)?

Answer 23

1. Westies
2. Cocker spaniels
3. Bassets

Question 24

Cryptococcus
How does it transport to the next host?
Hint: Construction workers are at risk!

Answer 24

It is found in soil and the feces of pigeons.
It can be spread by inhalation or open wounds.

Question 25

Who is at risk for the nasal form of Cryptococcus? Hint: fuzzy ears

Answer 25

Cats and koala bears

Question 26

Cryptococcus diagnosis methods (4)

Answer 26

1. Cytology (most common) 2. Serology 3. Antigen 4. Culture

Question 27

Cryptococcus diagnosis: Cytology

Answer 27

- Prolific in tissues - Characteristic thick capsule when stained - India ink or cotton blue

Question 28

What is the therapy for Cryptococcus? How long?

Answer 28

A combo of: 1. Debulking Sx when possible 2. Long-term medication - Azoles (anti fungal agent) - 3-12 months or more - Relapse is common

Question 29

What are Dimorphic pathogens?

Answer 29

Fungi that can exist in the form of both mold and yeast (yikes!)

Question 30

Dimorphic pathogen: Coccidiodes, what is it? Hint: S S Z

Answer 30

It is a soil fungus of lower Sonoran life Zone

Question 31

What happens to dog when they contract Coccidiodes? Hint: This can sometimes present as pneumonia because its an airborne disease.

Answer 31

Dogs commonly get lung or bone forms of disease from inhaling arthroconidia

Question 32

Howdo cats contract Coccidiodes? In what form do they get it?

Answer 32

Cats commonly get a skin form of the disease from puncture wound contaminations

Question 33

What is the therapy for Coccidioidomycosis?

Answer 33

1. Ketoconazole is effective & prevents disease from becoming systematic. 2. Bone & systemic forms MUST be treated or death is possible.

Question 34

T/F: Dogs w respiratory form of Coccidioidomycosis will recover w/o treatment

Answer 34

True! At least in most cases

Question 35

T/F: Fungal infections are usually slow growing

Answer 35

True

Question 36

T/F: Fungal infections do not have an intense inflammatory response from the body

Answer 36

False. They will cause an intense inflammatory response from the body!

Question 37

T/F: Cellular immunity is needed to clear fungal infections

Answer 37

True! The body needs strong, well programmed, and smart T-Cells. Fungal diseases can be very hard on young animals with building immune systems and immune compromised.

Question 38

T/F: Most fungal infections are not directly contagious, except dermatophytes

Answer 38

True! Dermatophytes is also a zoonotic disease

Question 39

T/F: Spores are not very resistant to disinfection and decontamination

Answer 39

False. Spores are very resistant! 10% bleach is usually effective to disinfect formites

Question 40

T/F: Most fungal infections can be treated fast and easily

Answer 40

False! Most require weeks to months of therapy to resolve them