Final answer:
In microbiology, Staphylococcus refers to a genus of halophilic and facultative anaerobic bacteria that are shaped like grape-like clusters. The most notorious species include Staphylococcus epidermis and Staphylococcus aureus, which are associated with nosocomial infections and various skin infections, respectively. The correct answer is C) A bacterium.
Step-by-step explanation:
In microbiology, Staphylococcus is a genus of bacteria. These bacteria are characterized by their spherical shape, form grape-like clusters when viewed under a microscope, and exhibit halophilic and facultative anaerobic properties. Although they belong to the class Bacilli, they are coccus-shaped rather than bacillus-shaped. The most well-known species within this genus are Staphylococcus epidermis and Staphylococcus aureus.
Staphylococcus epidermis is frequently associated with nosocomial infections, particularly those transmitted via medical devices inserted into the body. Similarly, Staphylococcus aureus is notorious for causing various skin infections and can be dangerous if it is antibiotic-resistant. It is a common bacterium that lives on healthy human skin but can cause serious infections if it enters the body through a wound. Therefore, the correct answer to the question 'What is a "staphylococcus" in microbiology?' is C) A bacterium.