- Coagulase Positive: converts fibrinogen to fibrin (red sea clotted)
- Protein A on S. aureus cell wall binds Fc portion of antibodies
- Catalase Positive (cat) (watch out in Chronic Granulomatous Disease where O2 dependent killing is defective)
- Beta-hemolytic (red bulb)
- Dx: Grows on Mannitol salt agar, ferments mannitol turning agar yellow
- Colonizes the nares of the nose
- Inflammatory Diseases
- Pneumonia (patchy infiltrate)
- Often secondary post-viral infection
- Septic arthritis, most common cause
- Abscesses
- Rapid onset, acute endocarditis, often IV drug abusers, R side heart problems: Tricuspid
- Toxin-mediated diseases
- Scalded-skin diseases (exfoliative toxin, protease)
- Toxic shock syndrome d/t toxic shock super-antigen (superhero cape)
- Food poisoning, rapid onset in 1-8 hrs after ingestion: mayo and unrefrigerated meats, more vomit than diarrhea
- MRSA: penicillin-resistant, alters penicillin binding proteins, Rx: vancomycin
- If Methicillin sensitive, may use Rx: Nafcillin "Naf for Staph"
- or for Cellulitis, Doxycycline (if not child or nursing)
http://www.emedicinehealth.com/slideshow_mrsa_pictures/article_em.htm
Commonly called Staph aureus.
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