Which organism is a common normal skin microbiota member among Staphylococcus species?

• A. Staphylococcus aureus
• B. Staphylococcus epidermidis
• C. Micrococcus luteus
• D. Propionibacterium acnes

Answer: (C)

On the skin, many bacteria live as normal residents, and within the Staphylococcus group the most common nonpathogenic skin commensal is Staphylococcus epidermidis. It sits on the surface of the skin and mucous membranes as a typical member of the normal flora, usually harmless in healthy people, and it helps occupy niches that prevent other, more dangerous microbes from taking hold. Staphylococcus aureus, while also a Staphylococcus species, is more often associated with infection when it breaches defenses. Micrococcus luteus is a different genus altogether, not a Staphylococcus, and Propionibacterium acnes (Cutibacterium acnes) is another common skin inhabitant that lives in hair follicles and is linked to acne. So the best answer, focusing on a common normal skin microbiota member among Staphylococcus species, is Staphylococcus epidermidis.