This Gram positive coccus is most frequently found in pairs and short chains of spherical or ovoid cells. Cells are catalase negative and exhibit facultatively anaerobic metabolism. The optimal temperature for growth is 37 C. It is common to the upper respiratory tract of man and less so in other primates. Can also be recovered from the environment and from body fluids of diseased individuals. Causative agent for strep throat, scarlet fever, rheumatic fever, glomerular nephritis, and a host of other infections.