Flashcards in skin 11: subQ fungal infections Deck (31):
all agents of subQ fungal infections
Sporotrichosis, Mycetoma, Lobomycosis, Chromoblastomycosis, Phaeomycotic cysts
source for these subQ agents ??
mode of entry??
Only ?? can display visceral organ involvement.
Plant material (splinters, thorns, etc)
Sporothrix schenckii, a *thermally dimorphic fungus*
contact with plant material and subsequent implantation of the organism through a trauma wound (e.g. rose thorn, wood splinter).
Sporotrichosis is usually a ??
What can occur in individuals who are immunosuppressed??
chronic infection characterized by nodular lesions of cutaneous or subcutaneous tissues and adjacent lymphatics that suppurate, ulcerate and drain (lymphocutaneous or gummatous sporotrichosis).
Visceral organ involvement (disseminated form)
Good for lymphocutaneous, fixed cutaneous and mucocutaneous forms.
*Grave for disseminated form*
Direct microscopic examination of pus, exudate, biopsy material and aspirates is best, and easily achieved with a fluorescent antibody staining technique. The organism is dimorphic, thus cultured at room temperature (25oC) and at 37oC.
also Sporotrichin skin test.
Sporotrichin skin test:
what is it used for?
A DTH response is positively associated with *less severe disease*. *Not useful for diagnosis*.
Serological tests against the yeast cell antigen are used to monitor the course of disease and effectiveness of treatment.
cutaneous leishmaniasis and
atypical mycobacterial infection, especially Mycobacterium marinum (fish tank cellulitis)
Amphotericin B in AIDS pts (ensure it does not become systemic)
heat about 39oC 3-4x/day on affected extremity (slows progression of lesion)
Mycetoma is an ??
infectious process with tumefaction (looks like a tumor), usually involving the foot or hand, caused by organisms that stimulate *grain formation* and eventually drain through sinus tracts in the skin. (sounds like actinomycosis)
Mycetoma grains comprised of ??
though to represent ??
referred to as the ??
the agent stuck in a matrix;
a precipitate of Ag-Ab complexes and Splendore-Hoeppli material deposition of eosinophilic material around the microorganisms
2 groups of orgs cause mycetomas: ??
a variety of bac and fungi (including Actinomyces israelii)
mycetoma is endemic in ??
the tropics and subtropics
(between the Tropics of Cancer and Capricorn).
More common in men than women, particularly those aged 20 to 50.
mycetoma generally presents as ??
and may persist ??
2/3 arise on the ??
a single lesion on an exposed site
foot. (Madura foot)
mycetoma starts as a ??
It grows slowly but eventually involves ??
what happens to the middle of the lesion??
small hard painless lump under the skin.
involves underlying muscles and bones.
The middle of the lesion caves in ulcerates and discharges pus, which contains grains.
mycetoma lesions eventually develops ??
sinus tracts (holes) which also discharge pus and grains.
The surface skin is scarred and pale. Considerable deformity often makes it difficult to walk; may cause no discomfort but it often itches or burns.
Secondary bacterial infection is common.
There is contiguous bone involvement, but visceral dissemination does not occur.
?? is a synonym for mycetoma of the foot only.
The diagnosis of mycetoma depends on ??
identifying grains. These are obtained using a needle and syringe to extract material from a soft part of the lesion under the skin or by collecting pus. Occasionally a skin biopsy is necessary.
Bacterial infections such as osteomyelitis, atypical
mycobacterium infection, tuberculosis, leprosy and syphilis
Prolonged treatment at high dosage is required because of poor penetration into the area of cyst and abscess formation, and even then, *surgical debridement and often amputation* are necessary.
Lobomycosis (Lobo's Disease) agent
most Lobomycosis infections are acquired where geographically??
South and Central America
Lobomycosis Clinical Manifestations
An extremely indolent, chronic, subcutaneous infection that usually begins as well circumscribed, indurated, asymptomatic keloidal nodules that develop into slowly growing tumors of the dermis, that present smooth, verrucoid or ulcerated surfaces.
Chromoblastomycosis (Chromomycosis) agents
several species of *pigmented* fungi.
Chromomycosis occurs where geographically??
Chromoblastomycosis clinical manifestations
A localized chronic infection of the subcutaneous tissues
characterized by raised lesions that may present a *cauliflower-like appearance.*
Over years, lesions enlarge to involve entire extremity.
antimycotic agents and surgery
Phaeomycotic cyst: Following implantation of the organism, what develops??
a well-circumscribed subcutaneous abscess with surrounding cyst