In the scientific name Streptococcus pyogenes, what is the genus?

• A. Streptococcus
• B. pyogenes
• C. Staphylococcus
• D. Streptobacilli

Answer: (A)

In binomial naming, the two words together identify a species, with the first word designating the genus—an umbrella group of closely related species—and the second word naming the exact species within that genus. In Streptococcus pyogenes, the first term, Streptococcus, is the genus. The second term, pyogenes, is the specific species epithet that identifies this particular organism within that genus. So the genus here is Streptococcus. Genus names are capitalized and usually written in italics, while the species epithet is lowercase. The other terms are not the genus: pyogenes is the species epithet, and Staphylococcus or Streptobacillus are different genera.