False-colour transmission electron micrograph (TEM) of the Gram-positive, branched (Y-shaped) bacterium Bifidobacterium bifidum. Species of Bifidobacterium inhabit the human gut, mouth and vagina and are rarely pathogenic. Such isolated infections due to Bifidobacterium include obstetric and gynaecological sepsis, peritonitis, pleuro-pulmonary infections, urinary tract infections, bacteraemia and endocarditis. Treatment is with penicillin. Magnification: x16,500 at 6x4.5cm size and x8250 at 35mm size.