Cutaneous -> Systemic Mycoses & Fungal-Like Pathogens (LeCuyer)

Question 1

Sporothrix schenckii - type of organism

Answer 1

Dimorphic fungus
- yeast

Question 2

Mucormycetes, pigmented fungi, oomycetes have what structure in host?

Oomycete is not an actual fungus

Answer 2

Hyphal

Question 3

Prototheca spp. = what type of organism

Answer 3

Algae

Question 4

What type of environment is sporothrix found in?

Severe granulomatous response to the disease

Answer 4

soil & dead vegetation; rose thorns

Cats: digging in soil -> nail beds

Question 5

Pathogenesis of sporotrichosis

Answer 5

Abrasion of skin / puncture -> cutaneous, lymphocutaneous, systemic disease. Cats > dogs. zoonotic!!

Sporotrichoid lymphocutaneous infection is a syndrome characterized by the development of superficial cutaneous lesions that progress along dermal and subcutaneous lymphatics.

Question 6

Why can you perform an impression smear from the draining tract of a patient infected with sporothrix?

Histoplasmosis also appears like this

Answer 6

B/c the fungus is NOT a part of the patient’s normal flora

Question 7

How are sporothrix infections treated?

Answer 7

Azole drugs, iodide drugs (dogs only)

Question 8

Mucormycosis
- source
- geographic location

Answer 8

• decaying plant matter,
• mostly found in tropics & subtropics (but they are ubiquitous and can be found anywhere)

Question 9

Mucormycosis
- pathogenesis

Answer 9

• The fungus hypal structures invade the walls of blood vessels => reduce the blood flow and eventually block all blood flow to the tissues
• animal is unable to recover due to fast turnover rate of hyphal invasion
• opportunistic / mostly affects immunosuppressed/immunocompromised dogs!

Question 10

Treatments & prognoses of Mucormycosis, Phaeohyphomycosis and Protothecosis

mucormycosis

Answer 10

Combo therapy required:
- surgery (limp amp) + azole or amphotericin B + tapering of immuno-suippressive drugs + addressing underlying disease / issues

Prognosis:
- mucormycosis = guarded if infection has invaded beyond the skin
- phaehyphomycosis = grave if infection has invaded beyond the skin
- protothecosis = grave

phaehyphomycosis

Amphotericin B b/c it works quickly – good for severe cases

Question 11

Phaeohyphomycosis
- characteristics
- habitat
- pathogenesis
- common signalment of affected pateint

Answer 11

• are pigmented fungi // produce melanin
• ubiquitous in the environment
• Pathogenesis: opportunistic fungi that cause cutaneous infections that develop into 2º disseminated systemic infections => grave prognosis
• immunocompromised or immunosuppressed patients

Question 12

Oomycosis
- colloquial disease name
- habitat
- pathogenesis
- species affected

Answer 12

-Swamp cancer
- warm FW; gulf states (habitat on aquatic plants)
- pathogenesis = requires damaged skin or mucosa in order for zoospores to invade! => invade cutaneously or gastrointestinally
- dogs, horses

Gastric oomycosis in a dog - dog ingested the zoospores which then invaded the stomach

Question 13

Why are oomycetes considered to only be “fungal-like”?

Answer 13

• Lack chitin
• Lack ergosterol
• Are more phylogenetically related to algaee & diatoms

Question 14

What does serology for oomycosis tell?

Answer 14

Whether antibodies to pythium are present for the disease’s GI from

Question 15

Describe the combination therapy + prognisis required for oomycosis

Answer 15

Question 16

Prototheca
- characteristics
- habitat
- pathogenesis + forms of disease
- species affected

Answer 16

Question 17

Identify

Answer 17

Prototheca spp.

Question 18

Public health concerns with protothecosis

Answer 18

Not generally spread from animal -> human, but can spread to humans via unpasteruized milk from a cow with protothecal mastitis