S. afermentans
S. aureus
S. auricularis
S. capitis
S. caprae
S. epidermidis
S. felis
S. haemolyticus
S. hominis
S. intermedius
S. lugdunensis
S. saprophyticus
S. schleiferi
S. simulans
S. vitulus
S. warneri
S. xylosus
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 completely 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.
Staphylococci can cause a wide variety of diseases in humans and other animals either through toxin production or invasion. Staphylococcal toxins are a common cause of food poisoning. The bacteria 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).
Staphylococci can also be found on the tips of the fingers. Most commonly it is found on the index finger as well as the thumb. This infection is known as a felon. As are many other Staphylococcus infections, felon is very painful and can be treated with antibiotics. Most S. aureus are penicillin resistant, but vancomycin and nafcillin are known to be effective against most strains.
Staphylococcus aureus shows beta-hemolysis on Sheep Blood Agar, however S. epidermidis is non-hemolytic on SBA. Both are positive for catalase production.