False colour transmission electron micrograph (TEM) of a single gram negative, non-motile, non- sporing bacterium, Calymmatobacterium sp.. C. granulomatis is responsible for the human sexually transmitted disease granuloma inguinale, which is characterised by a pimply rash on & around genitals, and which may develop into a granulomatous ulcer. Treatment is with antibiotics (tetracyclines and streptomycin). Individual bacterium are relatively large, being up to 1 x 1.5 micrometers in size. The exterior cell wall is covered by fine hair-like pili, which cause bacteria to adhere to other bacteria and foreign cells. Magnification: X 26,500 at 35mm size.