Propionibacterium acnes. Coloured transmission electron micrograph of a Propionibacterium acnes bacterium, in cross-section. It is associated with acne in humans. Formerly known as Corynebacterium acnes, it is a rod-shaped Gram-positive bacillus. The cell's genetic material is seen at centre (yellow). P. acnes is a part of the human skin microflora which breaks down lipid components of sebum. This bacteria is not found in children; colonization occurring at puberty and peaking around 16-17 years old. High numbers of P. acnes are thought to cause the inflammatory response of acne. Treatment is with tetracycline drugs. Magnification: x53,000 at 6x7cm size. x180,000 at 8x10"~PORTRAIT"