Proteus bacteria. Coloured transmission electron micrograph (TEM) of a section through Proteus sp. bacteria. These Gram-negative bacteria have two forms. A short bacillus (rod-shaped) bacterium (green) is dividing by binary fission to form two identical daughter cells. It uses its stubble-like fimbriae to attach to other cells and to substr- ates. The other larger form (orange) is covered in whip-like flagella with which it moves around and colonises new areas by a process called swarming. Proteus bacteria are normally found in soil, but also occur in the human intestine. They can cause urinary tract infections. Magnification unknown.