Final answer:
Staphylococcus aureus (S. aureus) is a Gram-positive bacterium that forms spherical cells and grapelike clusters, and it is a facultative anaerobe, usually found in aerobic conditions. A catalase test distinguishes it from other Gram-positive cocci like Streptococcus.
Step-by-step explanation:
Staphylococcus aureus (S. aureus) is a type of bacterium that falls under the category of Gram-positive bacteria. This classification is evident through its reaction to the Gram stain procedure, where it shows up as purple under a microscope due to the thick peptidoglycan layer in its cell wall. S. aureus exhibits a spherical cellular morphology and tend to form grapelike clusters. These bacteria are known for their role in various infections and their ability to ferment mannitol, which is utilized as part of the diagnostic process.
Staphylococcus aureus is also known to be a facultative anaerobe, which means it can grow in the presence or absence of oxygen, although it is typically aerobic. This characteristic, along with a catalase test, helps distinguish it from other genus of gram-positive cocci like Streptococcus, which is catalase-negative. Clinically, identifying S. aureus correctly is crucial due to its association with serious skin infections and potential resistance to antibiotics.