Cutaneous Microbiology and Immunology Flashcards
what are antimicrobial peptides important for
- innate immune mediators of skin
gram-positive bacteria predominate where on the skin
- dry areas
gram-negative bacterial predominate where on the skin
- moist areas
most bacteria are the in the superficial layers of the stratum ______ and in the upper parts of the ______-
- stratum corneum
- upper parts of hair follicles
what is the main aerobic bacterial resident of the skin
- staph epidermidis
what organisms colonizes normal skin in the nose, perineum, and vulva
- S. aureus
what organism is common on the skin of patients with atopic dermatitis
how does it occur?
- S. aureus
- reduce antimicrobial peptides
- chronic inflam allows bacterial and viral infection
what are G+, aerotolerant anaerobes prevalent in areas with sebaceous glands
- P. acnes (Propionibacterium spp.)
also known as Cutibacterium acnes
why are beta-hemolytic streptococci not common on normal skin
- inhibited by lipid
what is a cause of impetigo in kids
- group A strep
what are common inhabitants of the mouth that may rarely spread to the skin
- alpha hemolytic streptococci
S. viridians and S. pneumonia
fungi are found where
- under nails
what do keratinocytes have on them that allow them to contribute as an innate immune player
- toll like receptors (TLRs)
what do keratinocytes secrete that allow them to contribute as an innate immune player
- cytokines
- chemokine
what is the role of beta defenses and LL37
they are AMPs (Antimicrobial peptides)
- makes resistance difficult
- pokes holes in the membrane in irregular pattern
how does S. epidermis educate CD8+ T cells
- dendritic cells sample S. epidermiditis antigens
- present to CD8+ T cells
- induce IL17
- keratinocytes enhance barrier function and limit pathogen invasion
dysregulated innate immune responses in the skin result in what
- chronic cutaneous inflammation
more diverse skin flora correlate with _________
- disease remission
what do staphylococcus aureus and streptococcus pyogenes produce
- superantigens
- toxic shock toxins
how superantigen works
- binds outside of antigen specific pocket
- massive polyclonal expansion of T cells and “cytokine storm”
what does the exfoliative toxin of S. aureus cause
- scalded skin syndrome
role of S. aureus exotoxins
- cleave desmoglein causing intraepidermal splitting
how is S. aureus resistant to antimicrobial peptides
- binding and cleavage
- surface alteration mechanisms
superficial infections of dermatophytes are called
- ringworm
- tinea
