What bacteria causes strep throat?

Streptococcus Bacteria. More specifically Group A Streptococcus bacteria. Group A is a designation of a specific type of antigen in the cell wall that this bacterial group possess. The most common culprit to cause strep throat is the bacterium Streptococcus pyogenes. Generally, the beginning of a strep throat starts with nasal drainage down the throat. Because S. pyogenes is sometimes a normal flora found in a decent percentage of the population's nasal cavities when there is nasal drainage running down the throat that presents the opportunity for a pathogenic strain of S. pyogenes to move into an area of the body that it isn't supposed to be in. When it does that, it "moves" in to the throat area and begins beta-hemolysis causing the dotted, white throat that is characteristic of the disease.



Sorry for the long answer. The previous answer was so vague that I felt it needed to be vastly clarified.
Streptococcus causes strep throat.