Staphylococcus

Wikipedia, the free encyclopedia - Cite This Source

Staphylococcus (in Greek staphyle means bunch of grapes and coccos means granule) is a genus of Gram-positive bacteria. Under the microscope they appear round (cocci), and form in grape-like clusters.

The Staphylococcus genus includes thirty-one species. Most are harmless and reside normally on the skin and mucous membranes of humans and other organisms. Found worldwide, they are a small component of soil microbial flora.

Role in disease

Staphylococci can cause a wide variety of diseases in humans and other animals through either toxin production or invasion. Staphylococcal toxins are a common cause of food poisoning, as it can grow in improperly-stored food. Although the cooking process kills them, the enterotoxins are heat-resistant and can survive boiling for several minutes. Staphylococci can grow in foods with relatively low-water activity (such as cheese and salami).

Coagulase presence

Staphylococci may be classified as coagulase-positive and coagulase-negative, depending on the presence of coagulase.

  • Coagulase-positive staphylococci are mainly represented by S. aureus.
  • Coagulase-negative staphylococci are mainly all other species than S. aureus. They are the main type of bacteria colonizing the skin as human flora.

Biochemical identification

Staphylococcus aureus shows beta-hemolysis on Sheep Blood Agar, however S. epidermidis is non-hemolytic on SBA. Both are positive for catalase production.

See also

References



Wikipedia, the free encyclopedia © 2001-2006 Wikipedia contributors (Disclaimer)
This article is licensed under the GNU Free Documentation License.
Last updated on Wednesday March 12, 2008 at 05:20:51 PDT (GMT -0700)
View this article at Wikipedia.org - Edit this article at Wikipedia.org - Donate to the Wikimedia Foundation