Staphylococci Flashcards
- gram positive cocci
- arranged in clusters
- catalase positive, oxidase negative
- major component of normal skin and nares flora
staphylococcus
- most virulent species of the genus
- common flora on skin and mucus membranes
- spread by direct contact
- antibiotic resistance a major concern
staph aureus
foodborne s. aureus intoxication:
- source?
- transmissions?
- symptomes: rapid onset with _____ hours
- duration: _____ days
- treament?
source: meat, ham, pastries, and milk products left at room temp
transmission: infected food handlers
1-6 hours
1-3 days (n/v/d/stomach cramps)
symptoms, replace fluids, abx not helpful
adherence factor that binds IgG, Fc region of anitbody, prevents opsonization and phagocytosis of staph aureus
protein A
- recalcitrant to abx therapy
- result from attachment to device and biofilm replacement
- causes 76% of all orthopedic infections
- removal and temporary insertion of spacer, then replacement
device related staph aureus infections
- cellulitis, impetigo, folliculitis, abscess
- cellulitis: warm, red, soft swollen tissue, tender to touch
- impetigo: erythematous papules and pustules with yellow honey crusting, on face, large bullae
staph aureus skin and soft tissue infections
abscesses/furuncle more likely to be caused by staph aureus or group A strep?
staph aureus
- diffuse exfoliation (ritter’s)
- exfoliative dermatitis caused by ETA and ETB
- localized tender erythema, systemic spread, fever, blisters
- children less than 5yo
- mortality and scarring are rare
scalded skin syndrome
- superantigen
- sudden fever followed by headache, sore throat, diffuse red rash, skin desquamation
- shock within 48hr
staph aureus toxic shock syndrome
- binds to T cell receptor and MHCII molecules
- massive release of cytokines
- capillary leakage
- hypotension, shock, death
TSST-1 toxin
- infection of bone or bone marrow
- hematogenous spread or trauma
- sudden onset of pain over infected bone with fever, redness, refusal to bear weight
- in adults: crhonic, follows trauma or implanted device
osteomyelitis due to staph aureus
- most common cause of acute bacterial endocarditis
- high mortality, prompt antimicrobial therapy
- usually involves heart valves
s. aureus endocarditis
respiratory infections due to s. aureus?
pneumona, empyema, cystic fibrosis precedes entry of pesudomonas
defenses against staph?
- C3b opsonizes bacteria and enhances phagocytosis
- neutrophils: engulf bacteria, intracellular killing by O2 radicals
topical antibiotics for s. aureus?
bacitracin, mupirocin
