Micro: Lectures 25-26

points of entry in the skin

wounds, pores, circulation

physical blockage skin defense

keratin, cell sloughing (desquamation)

unfavorable environment skin defense

high salt, oils

antimicrobial skin defense

antimicrobial peptides (AMPs) to poke holes in cells

our normal flora (5)

staphylococcus epidermidis, corynebacterium diptheriae, propionibacterium acne, candida sp. (fungus), staphylococcus aureus

lesions

changes to skin caused by infection; include rashes, pustules, warts, abscesses

diagnostic indicators

disease specific signs; help us identify pathogens

macule

flat and discolored lesion; ex. vitiligo

papule

raised and solid lesion; ex. warts

vesicle

lesion filled with a clear fluid; ex. blister

pustule

lesion filled with pus; ex. acne

pus

dead WBC, bacterial/fungal cells

purulent fluid

contains pus

abscess

deep tissue pustule; decreased blood flow

considerations for treatment of abscesses

antibiotics don’t penetrate well; must drain to improve blood flow; the deeper in the skin the infection goes, the more serious it is

S. aureus protein A

blocks antibodies from binding to FC sites

Hospital-Associated (HA) MRSA

mecA gene; resistant to all antibiotics except vancomycin

Community-Associated (CA) MRSA

mecA and PVL genes; sensitive to other antibiotics besides methicillin

toxemia

toxin enters bloodstream; bacteria not present at the site of symptoms; bacteria not in the blood

scalded skin syndrome (SSS)

caused by S. aureus exfoliative toxin; bacteria colonize in intestine of newborns/ children <2; toxin enters bloodstream; skin peels off in sheets

toxic shock syndrome (TSS)

caused by S. aureus TSST-1 toxin; severe symptoms of fever, rash, skin shedding

GAS TSS

caused by toxemia associated with SPE A superantigen; similar to S aureus TSS but less common

SPE A

streptococcal pyrogenic exotoxin A (superantigen); rapid disease course

SLO

streptolysin; rapid disease course

exanthems

viral diseases characterized by a rash; all respiratory viruses; live attenuated vaccine; generally childhood diseases; ex. measles, rubella, roseola, chickenpox, fifth disease

severe outcomes of measles

pneumonia, immune amnesia (kills B and T cells), subacute sclerosing panencephalitis (SSPE)

subacute sclerosing panencephalitis (SSPE)

severe outcome of measles where virus replicates in brain and causes it to harden; always fatal

congenital rubella syndrome

mother infected in first trimester of pregnancy; miscarriage, still birth, blindness birth defects

mycoses

fungal diseases