Acne is not a contagious disease, and is not an infectious disease. You cannot get acne from touching the skin of an acne patient, or from using the phone previously used by someone who has acne.

It is a multi factorial condition, meaning that many factors play a role in the development of acne, and several of those factors have to exist in order for a person to have acne. The presence of a certain bacterium is one of those factors. Propionibacterium acnes (P. acne) are the bacteria associated with acne.

These bacteria live in the sebaceous follicles of every human being. It is part of the normal micro flora, which are bacteria that normally occur in specific parts of the body. People who have acne have higher numbers of these bacteria.

P. acnes bacteria are anaerobic, which means that they cannot survive in the presence of oxygen. In normal skin, the follicles are not obstructed with cell buildup and do not have abnormal amounts of sebum filling them. Even though there are P. acne bacteria present.

Open comedones are better known as blackheads. Histologically, they are a sebaceous follicle with a dilated follicle opening or ostium. The follicle is filled with a solidified plug made of dead cells imbedded in a semi-hardened mass of sebum. The head of the blackhead is dark in color, hence its common name. The black color of the tip is indicative of melanin presence and oxidation of the sebaceous plug.

The infundibulum is distended due to the pressure of the impacted debris. Because of the dilated ostia characteristic of open comedones, atmospheric oxygen penetrates the follicle. Therefore, due to the presence of oxygen deep in the follicle, open comedones rarely progress into inflammatory lesions. Closed comedones are often hard to see because they are most often flesh-colored small bumps that appear to be just under the skin. They are recognizable primarily because they cause an obvious bumpy skin texture.

They can be anywhere on the facial skin, but are most frequently seen in the cheek and chin area. Often they are accompanied by open comedones and other acne blemishes.

Closed comedones are much more likely to progress into an inflammatory lesion than open comedones. The tight, tiny opening of the follicle in a closed comedo does not permit aeration of the follicle, limiting oxygen exposure, and therefore setting the stage for P. acne proliferation and activity. Besides the lack of oxygen, in this tightly packed follicle is a large amount of solidified sebum, providing a source of nourishment for the P. acne.

The closed comedo becomes larger and more packed due to debris and inflammation from the metabolic activity of the P. acne, which produces enzymes that weaken the follicle wall. Eventually, the follicle wall ruptures. The immune system responds to this rupture by sending white (immune system) blood cells to the follicle to fight off the P. antes bacteria and also to contain the rupture.

The white blood cells travel through the bloodstream, which also transports red blood cells. The blood engulfs the ruptured follicle to bring the white blood cells to the site of the rupture. This is when the lesion turns red, due to blood engulfing the ruptured follicle.

At this point, the closed comedo is a papule, which is defined as a red raised acne lesion that does not have a pustular head. Papules are notorious for being red and sore. This is due to the pressure of the inflammation and the depth of the lesion in the skin, pressing on pain nerve endings. When the white blood cells enter the ruptured follicle to attack the bacteria in the follicle, many white blood cells are killed in the process. Many biochemical and enzymatic processes take place to break down the inflamed tissue, decrease inflammation, remove debris and bacteria, and begin to regenerate the follicle.

The result of these many processes is a liquefying effect of the follicle contents. Pus is a fluid that comprises millions of white blood cells mixed with this liquefied debris. A pustule is a follicle filled with pus forms after these processes take place in an inflammatory acne lesion.


A cyst is a pocket-like nodule that has an epithelial lining and a tremendous amount of inflammation. Massive amounts of white blood cells often form a boil-like lesion. The lesion eventually can rupture.

Cysts are responsible for many scars that can occur from acne. Cysts can be treated by a dermatologist who may inject the lesion with cortisone, reducing inflammation and causing the cyst to reduce in size in a few days. This treatment can help avoid scarring.

Cysts can be removed surgically, but this also can leave a scar. Nodules and cysts are both lesions that are too deep in the skin to be treated by estheticians. However, estheticians should know how to recognize them for proper referral to a dermatologist.