Flashcards in L 66 Dermatophytoses and Subcutaneous Fungal Infections Deck (30):
What are dermatophytes?
Fungi that invade keratin of skin, hair, nails
They have keratinase
What are the 3 genera of dermatophytes?
What is disease name for ringworm?
What are infective and diagnostic stages of ringworm?
Hyphae and arthroconidia
How is ringworm spread?
Person to Person, direct contact
Head on chair
Lab culture technique for onchomycosis/dermatophytes
Culture on Sabouraud agar or DTM=Dermatophyte Test Medium
DTM changes color to red in couple days, otherwise takes weeks to grow
10%KOH and cotton blue help to see arthroconidia
What fluoresce under wood lamp?
Some Microsporum species
Remember that not all surface fungi will fluoresce
What other fungal structures will be found in culture for identification?
Microconidium: small bud or ball coming off branch
Macroconidium: tennis racket looking thing
What are arthroconidia?
This is the same structure that Cocci has. The hyphae essentially segment and break off like joints and form arthrospores that exist in the environment and infect
What is trichophytin?
Crude antigen of dermatophytes
What are some sources of dermatophytes to infect humans?
How do the different dermatophytes present in the patient?
Clinical presentation of all the fungi in this group present similarly.
Tinea pedis may be caused by several fungi, but they will all present more or less the same and be treated the same
Like moist areas of body
more commonly tropical regions
Arthrospores are infective spores
Characteristics of lesions
Inflamed at edges with central clearing
Hair loss with pruritis–can cause black spots from the broken hair
Disseminated disease in HIV
Dermatophyte risk factors
Increased cortisol inhibits immune response
Athletics with body contact (wrestling)
Nail trauma, diabetes
Most common dermatophyte in humans
T mentagrophytes (second)
Dermal reaction to fungal antigens, lesions devoid of organisms, hypersensitivity reaction, result of excessive treatment, most common in tinea pedis
Target ergosterol in cell membrane
Best treatment by taking drug internally (orally) and killing them from inside out, topical often won't work
Amphotericin B, Nystatin
Griseofulvin, Lamisil (Terbinafine)
Remember that reinfection is likely! Throw away shoes etc.
Treating with itraconazole
Pulse dosing prevents liver damage
Keep skin dry
Don't share clothing or towels
Don't touch the lesions on others or on pets
Most common agent causing tinea capitis
T tonsurans Endo/Ectothrix
Treatment for tinea capitits
Agent for jock itch (tinea cruris)
Subcutaneous fungus attributes
Environmental in soil
Chronic and subcutaneous
Sporothrix schenckii characteristics
Thermally dimorphic (yeast and mold form)
Conidia – cluster resembles daisies
Chronic granulomas and necrosis
DOC: amphotericin B or itraconazole
Sporothrix schenckii pathophysiology
Traumatic inoculation–often a gardener or someone spending lots of time with soil or decaying plant material
Develops abscesses, nodules, ulcers
Streaks up lymphatics
Usually self-limiting, except in immunocompromised
Sporothrix schenckii diagnosis
Clusters of conidia on Sabouraud agar
What is a mycetoma?
Tumor like infection of fungus
Most common mycetoma in USA
Common foot disease?