Mycology 2

How would you describe Malasseziasis based on size and shape?

3.0-6.5 micrometers round to oval yeal cells with buds connected by a broad base at which collarette develop

How would you describe Candidiasis based on size and shape?

2-8 micrometer, single narrow based budding yeast cells can form pseudohyphae

T/F Fungal diagnosis must always be done in the lab

False, they do not always need to be done in the lab

What are the THREE categories of Dermatophytosis?

Anthropophilic (human)

Geophilic (soil)

Zoophilic (animal)

What are the THREE genera of Dermatophytosis?

Epidermaphyton spp

Microsporum spp

Trichophyton spp

What is the reservoir of M canis?

What is the host? (3)

cats

cats, dogs, horse, etc

What is the reservoir of Nannizzia gypsea (M. gypseum)?

What is the host? (3)

soil

cats, dogs, horses, etc

What is the reservoir of M nanum?

What is the host? (1)

soil, swine

swine

What is the reservoir of M gallinae?

What is the host?

chicken turkey

poultry

What is the reservoir of M. mentagrophytes?

What is the host? (5)

rodent

dogs, cattle, swine, horses, cats, other

What is the reservoir of M verrucosum?

What is the host?

Cattle

Cattle, sheep, goat

What is the reservoir of M equinum?

What is the host?

horses

horses

How is Dermatophytosis transmitted? (3)

direct contact

contact with infected hai

contact with infected fomite

What is the inactive form of Dermatophytosis?

arthroconidia

Conidia resistant to ____, susceptible to desiccation and ___ temp. Adhere to walls for ____

cold

high

years

What must Dermatophytosis do to establish infection?

must compete with natural host defense mechanism to establish infection

T/F Arthroconidia can tightly adhere but cannot break thru host defenses of dry skin, sebum, serum and can cause deep trauma

False, superficial trauma

What can enhance the binding of Dermatophytosis?

moisture

What part of the skin does Dermatophytosis infect?

stratum corneum, hair, nails

Dermatophytosis utilizes what as a nutrient?

keratin

How would you describe Dermatophytosis as it presents in humans?

red, circular, scaly rash with raised edges and clearer skin in the center often resembling a ring (Ringworm)

With Dermatophytosis, greatest inflammatory response at most recent area of infection emphasizing ____ appearance.

circular

What are the FOUR major clinical features of dermatophytosis?

folliculitis

kerion

pseudomycetoma

onchomycosis

What is the clinical presentation of Microsporum canis?

Classic presentation of alopecia w/ papules, scales & crusts. Hyperpigmentation

What is the clinical presentation of T. mentagrophytes ?

progressive alopecia, w/ dramatic scaling, inflammation & scarring

Can have hyperpigmentation & ulceration.

What depicts the severity of Dermatophytosis?

HOST RESPONSE

What is a well-circumscribed, raised, focal or multifocal cutaneous nodule?

kerion

What is a uncommon deep dermal and SUBQ fungal infection caused by dermatophytes?

pseudomycetoma

What is a fungal infection of the nail unit usually caused by dermatophytes?

onchomycosis

T/F You should always rule out dermatophytes as a possible cause in skin causes

True

What TWO ways would you diagnose onchomycosis?

Direct microscopic

Culture

What is a diagnostic tool that could cause a false positive in Dermatophytosis?

woods lamb

How do you diagnose Wood's Lamp?

UV light

False fluorescence occurs due to what FOUR things?

shampoos, lint, debris, topical medications

What are the FOUR things that can be used for a diagnostic workup for dermatophytes?

Direct microscopic exam

Cytology

Fungal Culture

Histopathology

What is a negative to fungal culture?

takes hella long

What are the THREE things that you can find by doing a SUPERFICIAL skin scraping, tape strip method, impression smears?

dermatophilus

Malassezia

Candidia sp

What would you find if you did a deep skin scarping?

Dermatophytes

What are the THREE things that you can do with a tissue biopsy?

bacterial culture

Fungal Culture

Histopathology

What type of mount do you use to diagnose Dermatophytosis microscopically?

What TWO things should you look for?

KOH Wet Mount

Look for: hyphae, arthroconidia

What is KOH staining of hair used for?

used to digest cellular material to ease visualization

T/F The fungal culture is time dependent upon the organism

True

What result would you get from a fungal culture in 3-4 week?

What about 6 weeks?

positive/negative culture

manual fungal idenification

Dermatophyte Test Media (DTM), contains ____ & inhibitors to ____ bacteria & saprophytes

nutrients

reduce

What are the TWO morphologically forms of Dermatophilus congolensis?

motile zoospore

Filamentous Hyphae

What FOUR animals is Dermatophilus congolensis most common in?

cattle

sheep

goats

horses

What THREE animals is Dermatophilus congolensis rarely seen in?

pigs

dogs

cats

Where will you find Dermatophilus congolensis lesions? (2)

dorsum

legs

T/F Dermatophilus congolensis has direct transmission only

False, direct and indirect

Can Dermatophilus congolensis be associated with zoonotic infection?

Yes

How would you describe the morphology of Dermatophilus congolensis?

parallel rows of G+ cocci appearing similar to railroad tracks

T/f Dermatophytosis is self limiting

True

What is the best way to treat Dermatophytosis?

topical, systemic & environmental. Clipping hair best. Removes fragile hair - source of spores & allows for penetration of topicals.

What can you bathe puppies and kittens in if they have Dermatophytosis?

lime sulfate

add slide 41 later

okay

What are THREE other names for Dermatophilosis?

Rain Rot

Rain scald

Streptotrichosis

What does Dermatophilosis infect and cause?

epidermis

exudative dermatitis

If there are Dermatophilosis lesions on the back, what caused them?

high rainfall

biting flies

If there are Dermatophilosis lesions on the head,ears, axillae, groin, scrotum, what caused them?

ticks

If there are Dermatophilosis lesions on the muzzle, lips, head, lower limbs, what caused them?

dry season

aniamal forage spiny plants

What also could be see with Dermatophilosis?

poor growth

decreased milk production

weight loss

What does the initial lesion of Dermatophilosis look like?

scab covering an ulcerative area

add differential

okay

How would you describe the scabs of Dermatophilosis?

cup shaped scabs with adherent hair

What kind of foot rot can be seen with Dermatophilosis?

strawberry foot rot

What is proliferative dermatitis affecting the skin from the cornet to the carpus or hock?

Strawberry Footrot

What TWO ways do we diagnose Dermatophilosis?

1. impression smear of moist surface of scabs

2. smear of ground up dry scab, stain, view

What is the therapy for Dermatophilosis? (3)

eliminate predisposing factors

remove crusts and bathe

Treatment with drugs

What are the THREE drugs that you can use to treat Dermatophilosis?

Penicillin

streptomycin

tetracycline/oxytetracycline