Which of the following is a correct abbreviation for Staphylococcus aureus?

• A. S. aureus
• B. S aureus
• C. Staphylococcus aureus
• D. Staph aureus

Answer: (A)

In microbiology, the correct abbreviated form uses the genus initial with a period, followed by the species epithet in lowercase, with a space between. So Staphylococcus aureus is written as S. aureus. The period after the initial signals that the genus has been abbreviated, and the species name remains in lowercase, which is the standard formatting for binomial names in scientific writing (often italicized in print, but plain text shows as S. aureus).

The other forms don’t fit this standard: leaving out the period after the initial breaks the clear abbreviation signal; writing the full genus name ignores the common abbreviation convention; and using a nonstandard shorthand like Staph aureus isn’t the formal abbreviation used in scientific contexts.