Gram positive organisms
Staphylococcus aureus

Author: Christopher Hale, M.D. (see Authors page)

Revised: 27 April 2016, last major update August 2013

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PubMed Search: Staphylococcus aureus[title]

Cite this page: Staphylococcus aureus. PathologyOutlines.com website. http://www.pathologyoutlines.com/topic/microbiologystaphaureus.html. Accessed October 23rd, 2016.
Definition / General
  • Gram stain: positive
  • Morphology: cocci in clusters
  • Facultative anaerobe
  • Part of normal flora of skin, mucus membranes, nasal passages
  • Greek "Staphyle" (grape) + coccus, referring to grape cluster-like morphology on Gram stain
  • Staphylococcal food poisoning
  • Staphylococcal scalded skin syndrome
  • Skin and soft tissue infections
  • Septic arthritis
  • Endocarditis
  • Bacteremia
  • Any body site may be infected
  • Culture conditions:
    • BAP (non-contaminated sites), colistin nalidixic acid agar (contaminated sites) or mannitol-salt agar
    • Chromogenic agars (J Clin Microbiol 2003;41:5695)
    • 34 - 37°C

  • Gram positive
  • Catalase positive
  • Coagulase positive (slide or tube test)
  • Mannitol fermenter
  • Novobiocin sensitive (S. saprophyticus is novobiocin resistant)
Clinical Images

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Colonies of Staph. aureus

ASM microbe library

Gross Description
  • Cream yellow to orange on BAP, smooth, beta-hemolytic
Micro Images

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Gram positive cocci in clusters

Gram stain of Staph. aureus at ASM microbe library

Molecular / Cytogenetics Description
Differential Diagnosis