Pathophys-Day 4 Infection Flashcards
What pathogens cause impetigo most commonly?
Staph aureus
Strep pyogenes
What types of impegito are there
Honeycomb
Bullous
usually on face
What is erysipelas?
STrep infection of superficial dermal lymphatics that shows sharply demarcated, raised borders
What is cellulitis?
Infection of deeper dermis (contrast to erysipelas) and subq tissue with POORLY demarcated borders, usually streptococcal
Erysipelas vs cellulitis
Erysipelas-superficial dermal lymphatics, SHARP borders
Cellulitis-POOR borders, deeper dermis
What is an abscess?
Collection of pus in dermis and SubQ tissue
Boils are also called
furuncle
How is a furuncle different than folliculitis?
Deeper - infxn extends into subq tissue
What is a carbuncle?
A super furuncle (multiple ones)
Pathogenesis of staph scalded skin syndrome
S aureus exotoxin binds desmoglein-1 and disrupts cell-cell adhesion
Who gets staph scalded skin syndrome?
Infants/kids
Also adults with renal failure (low clearance) and immunosuppressed
Scalded SS histology?
Granular layer split in epidermis; dermis lacks inflammatory infiltrate
Scalded SS presentation?
Diffuse generalized erythema
Mucous membranes uninvolved
Perioral/periocular crusting and radial fissuring
What are the three subtypes of necrotizing fasciitis?
I: polymicrobial
II strep
III gas gangrene
How is NF different than cellulitis?
Deeper plane of infection
What is the classic characteristic sign of necrotizing fasciitis?
Pain out of proportion to the clinical findings - intense tenderness, erythema, warmth, swelling
Skin turns blue/purple
What pathogen most commonly causes TSS?
Staph aureus, sometimes GAS
TSS presentation
Sunburn-like erythema, sandpaper papules, fever
What is a dermatophyte?
A superficial cutaneous infection of a fungus that digests keratin
What are the three divisions of dermatophyte?
Trichophyton, microsporum, epidermophyton
the most common dermatophyte
t rubrum
What are the consequences of tinea unguium?
Nail bed deformation
Hyperkeratosis
discoloration
Ringworm aka
tinea corpis and tinea facei
Jock itch AKA
Tinea cruris
What pathogen causes most cases of tinea capitis?
T tonsurans
Superficial fungal infection histopathology?
- Neutrophils sometimes in stratum corneum
- Fungal hyphae in stratun corneum/follicles - best seen with PAS STAIN
- Stain bright red-pink
Candidiasis populations
women - vulvovaginal
immunosuppressed
Tinea versicolor epidemiology and pathogenesis
Tropical regions
Altered pigment patches from overgrowth of Malassezia
The large herpesviridae includes which viruses?
HSV 1 and 2
VZV
EBV
CMV
All produce latent, incurable infxn
Which herpes viruses cause skin infection?
HSV 1 and 2
Pathogenesis of herpes infections (skin)
Latent infection in ganglia becomes symptomatic with fever, stress, trauma, cold, sunlight, menstraution, immunosuppression
What causes herpes labialis?
HSV1
What causes herpes genitalis?
HSV2
HSV initial infection presentation
Starts with prodrome of tingling/pain
HSV1: asymptomatic; HSV2: systemic fever/fatigue
HSV reactivation presentation
HSV1: painful GROUPED VESICLES with ulceration in 4-5 days
HSV2: similar but more mild
What is herpetic whitlow?
Digital herpes
What is eczema herpeticum?
HSV superinfection of atopic dermatitis
Treatment options for herpes?
ACV, ValACV, famciclovir, foscarnet, cidofovir
VZV spread
direct contact or airborne
VZV incubation
11-20 days
How does shingles appear?
Produces a painful prodrome, followed by a dermatomal vesicular eruption
What is a buzzword for zoster histopathology?
Multinucleated keratinocytes
Compare the two VZV vaccines
Varivax: good for kids
Zostavax: 60+ years old
Who gets molluscum contagiosum and what does it look like?
Kids
smooth, dome-shaped, umbilicated papules
Molluscum contagiosum histopath
intracytoplasmic inclusions within keratinocytes (Henderson– Paterson bodies)
HPV virus characteristics
unenveloped dsDNA
What are the domains of the HPV virus?
URR: upstream reg region
Early region: early proteins
Late region: late proteins
What are some important proteins in HPV?
E6 - degrades p53
E7 - inactivates Rb
Overexpression of E6 and E7 found in malignant tumors
What does HPV use to gain entry?
L1/L2 proteins
Where does HPV replicate?
Nucleus
Where does HPV migrate?
Laterally and migrates up toward suprabasal cell layers, where mature virion continues; particles are shed with desquamation of cornified layer
Which herpes causes palmoplantar warts?
HPV1
Which herpes causes common warts?
HPV2,4
Which herpes causes flat warts (verrucae plana)
HPV 3, 10
WHich HSV causes genital warts and which are associated with cervical carcinoma?
HPV-6 and 11 cause 90% of genital warts, whereas uncommon variants like HPV-16, 18, 31, and 33 are associated with an increased risk of cervical cancer.
Gardasil protects against which herpes?
HPV 6, 11, 16, 18
Cervarix protects against which herpes?
16 and 18
