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're a small component of soil microbial flora. Role in disease Staphylococcus can cause a wide variety of diseases in hum… (More on Staph)