Staphylococcus aureus (pneumococcus), colony morphology
Click picture to enlarge. Close window to return

Aureus means gold, so most Staph colonies are golden yellow. However, there are variants, which can be almost white. Beta-hemolysis on sheep blood agar is characteristic, as is a positive coagulase test. If the coagulase test is positive and colony morphology and Gram stain is typical, then the isolate can be called Staphylococcus aureus without any further testing. Many Staph species are coagulase negative, and these are often lumped together by the laboratory as "Staph, coag negative (SCN)", without any further identification. Rarely, speciation may be required.