263. Fungal Bacterial Infections Flashcards
Three groups of fungi that cause superficial infections
Dermatophytes - cause tinea
Malassezia spp.
Candida spp.
Tinea Capitis (what it is, KOH, transmission, bug, variants, tx)
What is a kerion?
KOH: spores inside hair shaft
Patchy hair loss
T: contact with animals, humans, fomites (shared clothes)
bug: Trichophyton tonsurans in US (M. canis in world)
Variants are seborrheic (dandruff), “black dot” (alopecia areata)
Tx: Topicals INEFFECTIVE (don’t penetrate hair), need systemic griseofulvin/terbinafine
Kerion: painful boddy inflammatory mass with broken hair follicles, pus discharging, high scarring risk
Tinea Pedia
what it is, KOH, Types, Complication
Athlete’s foot: Small itchy blisters on feet, some scales/vesicles/redness
KOH: septate hyphae, branching (beads on string)
Moccasin type: marginated scale shaped like mocs
Vesiculobullous Type: large vesicles/blisters
Onychomycosis: chronic fungal infection of nailbed, responds poorly to topicals, treat once you identify fungus (oral anti-fungals expensive, long, and interact with other drugs)
Tinea Corporis
what it is, skin, KOH, related condition
Ringworm, annular itchy lesion with central clearing
KOH: scrape from scaly red margin to ID
Tinea Cruris: “jock itch” - similar but in groin
Tinea Versicolor
what it is, skin, tx
Overgrowth of Malassezia (Pityriasis Versicolor) normal flora, usually in summer months
Variably colored round patches on trunk, readily scales when scraped (does not look scaly)
Tx: 2.5% selenium sulfide shampoo on body, use infrequently to prevent relapse
Diaper Candidiasis
skin, pathogenesis, difference from Irritant Diaper Dermatitis
Beefy red plaques with fine white scale in groin area, involves skin creases, satellite papules/pustules on inner thigh/abdomen
P: wet diapers not changed regularly = feces urease enzymes release ammonia from urine = acute irritant effect = epidermal disruption = fecal candida enter disrupted barrier
IDD: spares skin folds! DC does NOT
Cutaneous Candidiasis
fungi, tx
C. albicans: most common cause of superficial/systemic candidiasis; normal flora of mucous membranes of upper respiratory, GI, female genital tract
Tx: topical antifungals
Candida Intertrigo
where, assoc, KOH, tx, prevention
Candidiasis of large skin folds (groin, armpit, butt, breasts, abd fold)
Assoc with obesity, DM, warm weather (sweat)
KOH: pseudohyphae
Tx: topical antifungals
Prevention: keep areas dry, clean, cool, weight loss if obese
Sporotrichosis
agent, route of infection, skin
Sporothrix schenickii
deep fungal infection, grows in nature on decaying vegetable matter
Dermal nodule appears, followed by chain of secondary nodules along lymphatics (spirotrochoid spread)
Blastomycosis
region, sx, KOH
“Chicago Disease” common to US great lakes
infects lungs then disseminates systematically - skin lesions on face and extremities
KOH: broad based budding yeast
Bullous Impetigo
what it is, pathogenicity, skin
Bacterial infection caused by G+ bacteria, usually S. aureus
P: secreted exotoxins bind Dsg1 (superficial desmosomes) = blistering
S: crusted blisters on chest/abdomen with scaling, may start in compromised area (eczema)
Staphylococcal Scalded Skin Syndrome
what it is, pathogenicity, tx, difference from TEN
Toxin secreted to blood = widespread superficial blisters, skin peels away in sheets, negative wound cultures (exotoxin in blood)
P: Exfoliative toxins A+B - bind Dsg-1 in granular cell layer
Tx: ABx, supportive, fluid/electrolyte management
TEN: deeper redder peeling, necrotizing entire epidermis
SSS: partial/superficial epidermal split
Scarlet Fever
what it is, pathogenicity, ages, sx, skin, dx, tx
Strep. Pyogenes SPE-A,B,C superantigens trigger rxn
Ages 2-10
Sx: abrupt onset of pharyngitis, fever, headache, chills
Few days: White-strawberry tongue
Day 4-5: Red Strawberry tongue
Skin: Diffuse erythema with sandpaper quality spread from head/neck to whole body, markedly in skin folds
2-3 weeks: desquamation
Dx: +Strep culture from throat
Tx: Penicillin
Cellulitis
what it is, etiology, tx
Dermis infection from wound/fungal entry - spreading erythematous tender plaque - streaks of lymphangitis to draining lymph nodes
E: 80% G+ bacteria - GAStrep, S. aureus (P. multocida, E. corrodens)
Tx: ABx with G+ coverage, treat tinea pedis if present (fungal entry)
Erysipelas
what it is, pathogen, location
superficial cellulitis with marked dermal lymphatic involvement - edematous/raised skin, erythema with sharply defined margins
Pathogen: Group A Strep
Location: lower extremities + face
