Fungi Flashcards
Cutaneous Fungi?
dermatophytosis: Microsporum, Trichophyton, Epidermophyton
subcutaneous Fungi?
Sporotichosis and Chromomycosis
Systemic Fungi?
Histoplasma capsulatum, Blastomyces dermatidis, Coccidioides immititis
superficial fungal infection that causes dark brown to black painless patches on the soles of the hands and feet. this infection is caused by? disease name?
Tina Niger is the disease
caused by: Exophiala wernechii
(hypopigmented center with a hyperpigmention surrounding it. will look like hyphaw in KOH with spherical yeats.
disease name?
caused by?
pityriasis versicolor (multicolored) caused by Malassezia furfur
infections of the skin, hair, and nail. sereat keratinase to breat down keratin. infection names? caused by?
Dermatophytosis
common dermatophytes include microsporum, Trichophyton, and Epidermophyton.
disease within the horny layer of the skin. form a ring with a red raised border. the border is the active inflammation. this is ring worm.
Tinea Corporis (body)
Fungal disease red patches on the groin and scrotum
Tinea Cruris (groin)
athletes foot. between the toes and causes cracking and peeling of the skin. infection requires warmth and moisture, so it only occurs in those wearing shows.
Tinea pedis (feet)
mainly in children. appears like an expanding ring in the scalp. hair loss.
Infections of hair: tinea capitits (scalp)
fungal disease causing nails to be thickened, discolored, and brittle.
Infections of nails: tinea unuium
how to diagnose cutaneous fungi?
diagnosis: skin scrapings in KOH. it will digest the keratin and you can see the microscpoic hyphae. OR with a Woods light (UV at 365nm) certain microsporum sp will look bright green.
gain entrance following trauma to the skin. will normally remain localized to the subcutaneous tissue or spread along lymph to loacl nodes. they are normal soil inhabitants of low varulence.
Subcutaneous fungi
dimorphic fungi commonly found in soil and on plants (rose thorn splinters. this disease will occur in gardeners. following a prick from a thorn a subcutaneoud nodule gradually appears and becomes necrotic and ulcerates. will heal and new nodules pop up nearby along the lymph tracts of the arm. seens as a yeats at 37 degrees and 25 degrees reveals branching hyphae.
sporotichosis: (Sporothrix schenchii)
These are soil saprophytes found in rotting wood. infectoin following a puncture wound. initially small, violet wartlike lesion develops. months to years later the violet colrd lesions arise nearby.they cluster together like cauliflower. KOH skin scrappings reveal copper-colored scleriotic bodies.
chromomycosis: (philalophora and cladosporium)
all three are dimorphic fungi. they grow as mycel forms with spors at 25 degrees on sabouraud agar. at 7 degrees on blood agar they grow in the yeats form. this is DIMORPHISIM and it plays a part in causing infection. in their natural habatat (soil) they grow at mycelia and release spores into the air. spores are inhaled, and grow as yeats in the human at 37 degrees.
systemic: three main fungi cause systemic disease in humans: Histoplasma capsulatum, Blastomyces dermatidis, and Coccidioides immitis.
endemic to the southwestern US (Arizona, New Mexico, southern California, and northern Mexico) causes mild pneumonia in a normal US person. common opportunistic infection in AIDS patients from that area. dimorphic fungi
coccidioidomycosis (Coccidioides immitis)
all three systemic fungi are acquired from inhalation of spores. causing a local infection and then enters blood.
local infections that never spread person to person and NOT acid fast bacteria (unlike TB)
Coccidion and Histoplamin are like PPD and will be injected under the skin to know if ever exposed to the fungus.
Three possible clinical presentations:
- asymptomatic: most are like this and left untreated
2. Pneumonia: mile pneumonia with a fever, cough, and chest X-ray infiltrates. with TB like granulomas with calcifications that follow.
small percentage get chronic pneumonie or chronic cavitary pneumonie
3. Disseminated: rarely occurs, unless immunocompromised pt.
endemic to areas that drain the Mississippi. NOT ENCAPSULATED. within most bird droppings, pneumonia from cleaning chicken coops or spelunking.
histoplasmosis (histoplasma capsulatum)
endemic to areas that drain the Mississippi. isolated in soil and rotten wood. rarest are systematic fungal infections. rarely systematic when causing infections. most present as chronic disseminated disease with weight loss, night sweats, lung involvment, and skin ulcers. HARDEST TO GET AND HARDEST TO HAVE!
blastomycosis (blastomyces dermatitis)
three possible infections for normal people and can be systemic in the immunocompromised.
1. oral thrus: creamy white excudate on the tongue with a reddish base cover the mucus membranes of the mouth.
2. vaginitis: “yeast infection” vaginal itching and discharge (thick copius secretions wetting the underwear) speculum reveals inflammed vaginal mucosa and patches of cottage cheese-appearing white clumps affixed to the vaginal wall.
3. diaper rash: warm moist areas like diaper folds or skin fold in adults can become ren and macerated secondary to canida invasion.
Immunocompromised pts:
1. Esophagitis: extension of thrush into the esophagus causing burning substernal pain worse with swallowing.
2. disseminated: retinal must be examined. in the blood is NEVER NORMAL.
Systemic canida (canida albicans):
how to diagnose canidia?
Diagnosis: KOH preperation of scin scaping or with stains and cultures of biopsied tissue or blood. beta-D-glucan can be measured in blood. part of the fungal wall for invasive fungi.
first in the US in 1999. C. neoforms in more widespread and more common species to cause infection in humans. these are polysaccaride encapsulated yeast that are inhaled into the lumgs but the major manifestation is meningoencephalitis (NOT pneumonia). found in pigeon droppings. inhaled and often asymptomatic, yeasts spread to blood, then the brian.
subacute chronic meningitis: headache, nausea, confusion, staggering, gait, and/or cranial nerve deficits. fever and meningismus can be mild. cryptococcal meningitis can be fatal due to brainstem compression.
cryptococcosis (Cryptococcu Neoformans and Cryptococcus gattii)
Cryptococcus diagnosis?
Diagnosis: lumbar puncture. India ink stain shows yeasts cells with a surroudning halo (the polycacharide capsule). antigen test for polysaccaride antigens. culture to confirm diagnosis.
