Scanning Electron Micrograph (SEM) of Streptococcus pyogenes, a spherical gram-positive bacteria that grows in long chains. Healthy humans may carry these bacteria harmlessly in the throat or nose. Phatogenic strains of S. pyogenes, however, cause infections of the skin (including impetigo), the uterus following childbirth (puerperal sepsis), and the bloodstream (septicaaemia). S. pyogenes accounts for the high incidence of sore throats, tonsillitis, and middle ear infections (otitis media) in children. Treatment is with penniciline drugs.