DR KARI LOUNATMAA / SCIENCE PHOTO LIBRARY DR KARI LOUNATMAA / SCIENCE PHOTO LIBRARY
Streptococcus pyogenes bacteria. Transmission electron micrograph (TEM) of a section through Streptococcus pyogenes bacteria. The bacteria at lower centre are dividing by binary fission. These gram-positive bacteria are rounded or spherical cocci. A cell wall (dark grey) surrounds the bacteria's cell contents. Many humans may carry these bacteria harmlessly in their throat or nose. Pathogenic strains however, cause skin infections such as impetigo, uterine infection after childbirth, and blood poisoning (septicaemia). They result in sore throats, tonsillitis and middle ear infections (otitis media) in children. Magnification: x200,000 at 8x10 inch size.
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