What size is strep throat bacteria?

The size of Streptococcus pyogenes, the bacteria that causes strep throat, can vary. On average, S. pyogenes bacteria are about 1-2 micrometers (µm) in diameter. This means that they are too small to be seen with the naked eye. They typically appear as spherical or cocci-shaped cells under a microscope. In chains or pairs, S. pyogenes bacteria can form colonies up to several millimeters in size, creating the visible signs of strep throat, such as white or yellow pus on the back of the throat.