Skin Infections Flashcards
Describe the natural resistance of human skin
Human skin is the first line of defense againstmicrobial infection via
- physical barrier
- secreting low pH sebaceous fluid and fatty acids along with antimicrobial peptides to inhibit pathogen growth
- By possessing its own normal flora, thus deterring colonization by other pathogens
Impetigo looks like?
Honey colored crusting of the skin
Who is infected with impetigo most commonly?
young children…
Gnerally on the face
What causes impetigo?
Strep pyogenes and staph aureus
What is Erysipelas
streptococcal infection of teh superficial dermal lymphatics that demonstrates sharply demarcated raised borders
Cellulitis
Infection of the deeper dermis and subcu tissue qith poorly demarcated borders. Vast majority of cases are streptococcal in origin
Abscesses are
collections of pus in dermis and sub cu
Folliculitis
infection of hair follicles in the epidermis
Furuncle
Deeper involvement of hair follicle. Also called a boil
Carbuncle
adjacent furuncles coalesce into a single inflamed area
Staph scalded skin syndrome caused by
Staph aureus toxin
Usually scalded skin syndrome is seen in
young babies or adults with renal failure
Why adults with renal failure
Can’t clear the toxin
Clinical features of scalded skin
generalized redness (erythema) perioral and periocular crusting and radial fissuring with mild facial swelling
NEcrotizing fascitis
widespread necrosis
Type I- polymicrobial
Type II- strep
Type III- gas gangrene
Pain that is out of proportion
Necrotizing fascitis
Toxic Shock Syndrome
Caused by staph aureus which produces a TSST-1 toxin and less commonly by group A strep
Toxic shock syndrome signs
fever, strawberry tongue, sunburn-like erythema and sandpaper papules,
Treatment of Toxic shock
antibiotics and remove the nidus of infection
Cutaneous fungal diseases divided into three categories
superficial, deep, systemic
Superficial infections are confined to what space?
dead keratinous tissue, the epidermis, and hair follicles
Whats a dermatophyte
fungi that digest keratin as a nutrient. These fungi colonize the highly keratinized stratum corneum or outermost layer of the skin, as well as other keratinized structures such as the nail plate and hair follicles
Three genera of dermatophytes
Trichophyton, Microsporum, Epidermophyton
Tinea pedis
Athletes foot, superficial infection of the foot. Mostly caused by dermatophytes
Tinea ungium
infection of nail plate or bed. Leads to onchodystrophy (nail bed deformity) with thickening (hyperkeratosis) of the nail bed
Tinea corporis
tinea on the trunk or limbs…ring worm
Tinea facei
Tinea on the face
Tinea cruris
jock itch…does not effect the scrotum or penis
Tinea capitis
scalp or hair
Tinea capitis most often caused by
T tonsurans
Candidiasis most often caused by
candida albicans
Candidiasis most often affects
skin, mucous membranes. Gi tract, nails
Candidiasis is most common in
females (vulvovaginal candidiasis) and immunosuppresed patients
Tinea versicolor
Harmless skin disease found in tropics
Characterized by overgrowth of malasezzia (fungus found on the skin of many animals and humans) this leads to hypo or hyper pigmented skin
HSV-1 and HSV-2 establish primary infection how
through mucosa or abraded skin, they then lie dormant in the nuclei of nerves where they lay dormant and multiply
Recurrence is sparked by
stress, fever, trauma, UV light, menstruation, or immunosuppresion
Herpes labialis
vesicular or ulcerative lesions of the oral cavity or perioral skin and mucoaa
HSV-1
Herpes genitalis
HSV-2 mostly, increasing 1
Primary HSV-1 infections
asymptomaic
Primary HSV-2
severe, painful vesicles formation, and ulceration
Major finding on molluscum contagiosum histology
Eosinophillic cytoplasmic inclusions within keratinocytes
E6 in HPV
degrades P53
E7 in HPV
Inactivates Rb
Overexpression of E6 and E7 leads to
Tumors
How does HPV gain access to basal keratinocytes
Comes in through minor abrasions in the skin or mucosa. Transmitted by direct or sexual contact.
Where does HPV replicate
In the nucleus
It is a very simple circular double stranded DNA virus with an icosahedral capsid
Its naked so it can survive well.
What HPV strains cause warts on fingers
HPV1
What HPV strains cause common warts on other places of the body
HPV2-4
Flat warts
HPV 3-10
HPV genital warts
6 and 11
cervical cancer
HOV 6, 11, 16, 18
How do HPV vaccines work
self-assembly of the L1 protein into virus like particles
Gardasil protects against
6, 11, 16, 18
Cervavix
16, 18
