Which of the following statements about staphylococci is TRUE?

• A. They are bacteria
• B. They are viruses
• C. They are fungi
• D. They are protozoa

Answer: (A)

Staphylococci are bacteria. They are single-celled organisms with a simple cell structure and walls, typically appearing in grape-like clusters under the microscope. They are classified as Gram-positive, which is a characteristic way to identify them in the lab. This group includes species such as Staphylococcus aureus and Staphylococcus epidermidis, which can be part of normal skin flora or cause infections when they invade the body. They are not viruses, which are noncellular and require a host cell to replicate; they are not fungi, which are eukaryotic organisms with more complex cell structures like hyphae and chitin in their walls; and they are not protozoa, which are single-celled eukaryotes with varied motility and life cycles. Therefore, the statement that they are bacteria is correct.