-
structure of the skin - intact barrier
- epidermin - avascular, includes many layers of dead cells, epithelial
- dermis - vascular, connective tissue
-
skin natural protection
- sweat - contains salt, acids (ph of skin ~ 5), and lysozyme (anti microbial)
- tears - lysozyme
- sebum - oil, breaks down into fatty acids that are antimicrobial
-
normal microbiota of skin
- Gram negatives - pseudomonas (likes warm moist environment), janthinobacterium
- gram positives - staphylococcus epidermitis, staph aureus (moist, mucous membranes), strep species (mouth)
-
bacterial infections of the skin
- acne
- impetigo
- erysipelas
- scalded skin syndrome
- folliculitis
- abscesses
- cellulitis
- necrotizing fascites
- gas gangrene
- leprosy
-
acne
- inflammed papules (bumps) or pustules (pus filled) on the skin
- sebum becomes trapped in pores and bacteria feed on it
- population increases and causes inflammation; more oil = more acne
- cause: propionibacterium acnes - gram + bacillus
- factors: hormones, cleanliness
- treatments: topical or oral, UV
-
impetigo
- small break in skin becomes infected, crust over and ooze clear fluid
- causes: 2 possible, both gram +. 1) strep pyogenes 2) staph aureus
- treatment: topical (bactroban or altabax), oral (cephalexin)
-
erysipelas
- deeper, enters via epidermis and gets into the dermis
- symptoms: red, hot, swollen, fever & chills if it enters blood
- cause: strep pyogenes
- treatment: penicillin
-
scalded skin syndrome
- red skin peels away
- cause: staph aureus; exfoliative toxins cause outer layers to separate and peel off
-
folliculitis
- inflammation of the hair follicle or glands
- looks like chicken skin
- cause: staph, strep
-
abscesses
- accumulation of pus in a lesion (fibrous)
- cause: staph aureus
- furuncle: single follicle or gland; often buttocks, axillae, or on back of neck
- carbuncle: deeper and larger
-
cellulitis
- non pus forming infection of dermin and subcutaneous layer, can enter blood stream
- lymphangitis: red lines radiating from site
- cause: staph aureus or strep pyogenes (pus forming)
-
necrotizing fascites
- cause: strain of bacteria that can break down connective tissue; very invasive
- hyaluronidase: breaks down connective tissue
-
gas gangrene
- myonecrosis: destruction of tissue and muscle
- produces large amounts of gas; foul smelling
- cause: clostridium perfringens- anaerobic spore forming bacillus; alpha toxin - RBC lysis, edema, tissue damage; collagenase & hyaluronidase - breaks down connective tissue
- treatment: large doses of penicillin
- hyperbaric O2 chamber - lethal to organism
-
leprosy
- cause: mycobacterium leprae - acid fast bacillus, slow grower, prefers cooler temp
- two forms: a) tuberculoid leprosy: local, tubercle forms in skin, may cause nerve damage. b) lepramatous leprosy: systemic, extensive skin damage at the periphery
- transmission: nasal secretions and skin to skin; takes 3-5 years for infection to grow
- treatment: multi drug long term therapy; rifampin, dapsone and clofazimine
-
viral infections of the skin - vesicular rashes
- vesicular rashes - fluid filled vesicles
- chicken pox
- shingles
- smallpox
- monkey pox
- fever blisters or cold sores
-
viral infections of the skin - maculopapular rashes
- maculopapular rashes: don't fill w/ fluid, no vesicle, just raised pink/red bumps
- measles (rubeola)
- rubella (german measles)
- roseola
- fifth disease
-
chicken pox (varicella zoster)
- human herpes 3 virus, varicella zoster virus
- herpes viridae - DNA viruses
- capable of lysogeny (laying dorment)
- transmission: resp. droplets, and lesions
- incubation: 10-20 days
- contagious 24 hours before rash until lesions dry up
- rash: macules (flat pink spots) "then" papules (raised bumps) "then" vesicles (fluid filled)
- treatment: self limiting w/out complication, comfort
- vaccination: varivax; recommend for all children
-
shingles
- VZV activates after latency in the CNS
- migrates down a spinal or cranial nerve to the dermatome
- herpes zoster: creeping rash in a belt pattern
- zostavax: vaccine for 60+ to reduce the risk of shingles
-
small pox (variola)
- cause: smallpox (variola) virus; poxviridae (DNA viruses)
- transmission: resp. droplets and fomites (inanimate objects)
- two forms: major- highly virulent, leads to toxemia, (vascular) shock, intravascular coagulation, rash. minor - less rash, milder illness
- rash: macules to papules to vesicles to pustules
- pustule: lesions filled w/ pus (WBC, debri, bacteria, etc) odorous
- vaccination: developed by Edward Jenner (doctor); observed the milkmaids who had suffered from cow pox didn't contract small pox; used cowpox virus (vaccinia: vacc = cow) to protect/vaccinate people
-
monkey pox
- simular to small pox but milder
- transmission: zoonotic; from animal w/ monkey pox; come in contact w/ blood, body fluids, or rash
- 2003 pet prairie dogs that were sick
- can spread human to human
- cause: monkey pox virus; poxviridae
-
fever blisters or cold sores
- cause: human herpes simplex virus type 1
- vesicle erupts, crusts over and heals in ~ 1 week
-
measles (rubeola) or red measles
- cause: measles (rubeola) virus; member paramyxoviridae; RNA virus
- pathology: koplik spots: mucous membrane in mouth, red patches w/ white spots; rash (exanthema) starts at head and spreads; self limiting
- vaccine: part of MMR; live attenuated
-
rubella (german measles)
- cause: rubivirus; togaviridae; enveloped RNA
- transmission: resp. droplets; transplacental transfer
- pathology: contagious - 2weeks before and after 3 day rash; macules (pin/red spots for 3 days); relatively mild
- congenital rubella syndrome: cardiac abnormalities, deafness, blindness, and mental retardation
- vaccine: MMR; live attenuated
-
TORCH
- teratogenic viruses
- toxoplasmosis
- other
- rubella
- cytomegalovirus
- herpes
-
teratogen
any agent that causes congenital defects
-
roseola
- childhood illness
- endemic
- cause: HHV6; herpesviridae; DNA
- symptoms: high fever, sore throat, swollen lymph nodes & a faint rash on face, neck, chest, and thighs
-
fifth disease
- cause: B19 virus; parvoviridae; DNA virus
- pathology: low fever & malaise for 5-10 days; erythema infectiosum - red rash on cheeks and other parts of body; can be aggravated by sun and can persist for weeks
- sequelae: arthritic symptoms
- pregnant: can cause stillbirth
-
viral skin infections with wart-like eruptions
- warts
- molluscum contagiosum
-
warts
- benign epithelial growths
- cause: HPV (human papilloma virus); papillomaviridae, DNA virus
-
molluscum contagiosum
- cause: molluscum contagiosum virus; poxviridae; DNA virus
- transmission: personal direct contact, STD, formites
- pathology: incubation - 4 to 7 weeks; untreated can last for months; children 1-10 year old
-
fungal infections of the skin
- dermatophytosis
- pathology: tinea pedis - athletes foot; tinea capitis - head/scalp; tinea corporis - body; tinea cruris - jock itch; tinea unguium - nails
- cause: 3 different genuses - trichophyton, epidermophyton, microsporum
- treatment: skin - topical antifungal; "azole"s; nails - oral, 6-12 weeks
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