What two organisms causes strep throat?

Strep throat, also known as streptococcal pharyngitis, is typically caused by the bacterium Streptococcus pyogenes, commonly known as group A Streptococcus (GAS). Occasionally, other strains of Streptococcus, such as Streptococcus dysgalactiae subsp. equisimilis (group C Streptococcus), can also cause strep throat.