Fungi Flashcards
Mycoses is what
fungal infections
Cutaneous mycoses
infections of skin, nails, and hair
generally limited to keratinized layers, epidermis, and dermis (generally outer layers)
Cutaneous mycoses - caused by
a group of organisms collectively referred to as dermatophytes (involve the skin)
Cutaneous mycoses - causes by more than 2 dozen species of
More than 2 dozen species of microsporum, trichophyton, and epidermophyton
Capable of degrading and utilizing Keratin as a nutrient source
Dermatophytes - 3 types
geophilic - found in soil
zoophilic - associated with animal contact
anthropophilic - person to person contact
Dermatophytes - worldwide distribution
20% of US infected at any given time
more prevalent in warm moist areas
predisposing factors = closed shoes, community shower
Dermatophytes - clinical syndromes typically evoke what
an inflammatory reaction involving underlying and surrounding tissue - circular lesions like ringworm are common
Dermatophytes - clinical syndromes - infections are characterized by what
itching and scaling of the skin
secondary bacterial infections are common
Dermatophytes - clinical syndromes - clinical manifestations of infection are often referred to as
Tinea (latin for worm)
Followed by a modifying word to describe the clinical manifestation or anatomical location
Tinea pedis
Feet - “athletes foot”
Generally a chronic infection
Classic presentation is between tow webs (can also be on heel or side of foot and can spread to nails)
Secondary bacterial infection is common
Tinea corporis
Torso, arms, and legs - “ring worm”
Classic presentation is a red, round, scaly patch with a raised border
Inflamed periphery with pustules
Can occur anywhere, but typically on trunk
Tinea capitis
scalp, eyebrows, lashes Scalp infection Distinct scaly lesion Patches of hair loss Involvement of entire scalp Fungal elements can surround the hair shaft or be present within the hair shaft
Tinea capitis - FAVUS
mass of hyphal elements surrounding the base of the hair shaft
caused by a certain species of trichophyton
Tinea cruris
Groin
lesions present in the groin
90% occur in men
secondary infection is common
Tinea unguium-onychomycosis
nails
infection of the nail plate and nail bed
hyperkeratosis and discoloration
dry, crackled, brittle, and disfigured nails
Common in pts with diabetes and AIDS
TX difficult because much deeper when in nail
Diagnosis of dermatophytic infections
mostly on presentation
need to determine the why - determine source, confirm differential, and anticipate response to therapy
Diagnosis of dermatophytic infections - hOW
direct observation of fungal elements in skin scrapings, nail or hair samples
Identification through culvitation
Diagnosis of dermatophytic infections - Woods lamp
some species of microsporum will cause infected hairs to grow when held under UV light
Tx of dermatophytic infections
may involve application of exfoliating agents as well as topical azoles
Azoles interfere with the synthesis of components of the fungal cell membrane
Tx of dermatophytic infections - specifically capitis
griseofulvin is frequently used with capitis
Is thought to interfere with fungal cell division
Tx of dermatophytic infections - specifcally unguium
difficult and may require long term administration of oral antifungals (which can lead to damage to internal organs)
Candidiasis caused by
several yeast of the genus candida
Most candidiasis infections are caused by
C albicans
Considered normal flora in skin, mucus membranes, GI tract
Also present in environment (doorknobs, carpet)
Candida can exist in
yeast, pseudohyphal, and hyphal forms
Yeast = normal flora
Hyphal forms = tissue
Cutaneous candidiasis are what? where do they occur?
skin and nail infections
body folds or areas that are moist or frequently become wet (diaper rash, dishwasher hands)
Cataneous candidiasis - may present as
papules or confluent plaques
redness, tenderness, and cracking
Chronic mucocutaneous candidiasis are what
superficial infections at several anatomical sites - mouth, face, finger nails
Chronic mucocutaneous candidiasis - disease associated with
particular T cell deficits and endocrine disorders
Chronic mucocutaneous candidiasis - response to infection
Granulomatous response to infection
disfigurement and discomfort
Disseminated Candidiasis - Factors
Increase in colonization (due to disruption of normal flora)
Breakdown of normal physical barriers (burns, traums, catheterization)
Immune suppression
Disseminated Candidiasis - At risk
Newborns
Surgery and burn patients
Transplant recipients
Patients receiving chemotherapy
Disseminated Candidiasis - spread
hematogenous spread of organisms to liver, spleen, lungs, brain, eyes, bones, joints…
Disseminated Candidiasis - tx
intravenous amphotericin B tx with or without fluconazole is current recommendation
Tx is challenging because can be toxic to patient
