1. Gram Stain
    GPC usually in clusters but can be in tetrads.
  2. Media appearance for each staph
    1-3mm round, smooth, convex,glistening, opaque,entire edge, butyrous (butter like) consistency.

    • BAP:
    • aureus: may be yellow and have small zone of beta hemolysis.
    • epidermidis: white colonies, usually nonhemolytic.
    • saprophyticus: often pigmented - yellow, orange, tan

    • MSA: is selective & differential media:
    • aureus: ferments manitol, so colonies will change from red to yellow
    • others staphs: Do NOT ferment manitol, so colonies stay red.
  3. Pathogenicity for S. aureus
    • Suppurative cutaneous infections
    • Toxic shock syndrome
    • Food poisoning
  4. Pathogenicity for S epidermidis
    Usually normal pathogen. Common contaminate. But those that are infectious:

    Come from hospital acquired nosocomial UTI
  5. Pathogenicity for S. saprophyticus
    Causes UTI in young sexually active women or catheterized elderly men.
  6. Tests for S aureus
    • Positive:
    • Coagulase, DNase, Catalase
    • Ferments Manitol on MSA changing colony from red to yellow.

  7. Tests for epidermidis & saprophyticus
    • Negative:
    • Coagulase
    • Positive:
    • Catalase

    Non Motile

    • S. saprophyticus: resistant to Novobiocin
    • S. epidermidis: suseptible to Novobiocin
  8. 3 Types of toxins for S. aureus
    • Enterotoxins: Heat stable exotoxins that cause diarrhea & vomiting. Are performed in foods. Appear 2-8 hours after injestion. Resolve within 8 toxic shock syndrome.
    • Epidermolytic toxin, sloughing of the skin, widespread systemic immune response.
    • Exfoliative toxin: Similar to TSST-1, but differnt site on skin.
    • Cytolytic toxin: Extracellular factors that affect RBC's and WBC's
    • alph: detryos RBC's,plt's,tissue
    • beta: destroys RBC's
    • Gamma: causes injury, less letahal
    • Leukocidin: lethal to PMN's
  9. Enzymes for Staph
    • Coagulase: cuases coagulation of surroundings
    • Hyaluronidase: hydrolyzes hyaluronic acin in connective tissue
    • Lipase: aids colonization by actin gon sebaceous glands.
    • FAME: breaks down anti-stahylococcal lipids made by the host.
  10. How is Protein A produced from S. aureus?
    • S. aureus cell wall
    • Binds Fc portion of immunoglobulin (avoid phagocytosis.
  11. Selective Media
    • MSA
    • CNA
    • PEA
    • Chromagar
    • Chromagar MRSA
Card Set