Micro - staphylococci
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- What are the morphological characteristics of S. aureus? What are its growth characteristics in culture?
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*G+ cocci
*B-hemolytic
*catalase +
*coagulase +
*will grow on mannitol salt agar - S. aureus contributes to a number of disease states. Name 3 that are on or very close to the skin.
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*pyogenic abscesses
*folliculitis
*impetigo
*cellulitis - What are 4 deep or systemic infections caused by S. aureus?
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*pyogenic abscess
*septicemia
*osteomyelitis
*endocarditis
*mastitis
*meningitis - What are three dieases mediated by toxins produced by S. aureus? What are the toxins associated with each?
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*staphylococcal food poisoning - enterotoxin
*scalded skin syndrome - exfoliatin
*TSS - TSST-1 - How does protein A add to the virulence of S. aureus?
- It binds the Fc region of Ig's and prevents them from opsonizing the bug.
- What controls the expression of the virulence factors of S. aureus?
- Accessory gene regulator.
- Name 3 virulence factors for S. aureus that begin with "c". What does each do?
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*capsule - antiphagocytic
*catalase - neutralizes H2O2
*coagulase - promotes clotting - What kind of resistance does S. aureus have? What is the mechanism here?
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*PCN resistance - due to B-lactamases
*methicillin - due to PBP mutation - How should infections with S. aureus be treated?
- Abscesses should be surgically drained and debrided.
- What type of disease is S. saprophyticus associated with?
- UTI in young, healthy, sexually active women.
- What type of nosocomial infection is S. epidermidis associated with? What are the more serious sequelae of these infections?
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*Infections of implanted devices
*endocarditis and septicemia - What is the primary virulence factor of S. epidermidis?
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*slime layer promotes adherence
*biofilm growth