Abscess | Research & Encyclopedia Articles

Abscess

An abscess is a pus-filled sore, usually caused by a bacterial infection. It results from the body's defensive reaction to foreign material. Abscesses are often found in the soft tissue under the skin, such as the armpit or the groin. However, they may develop in any organ, and are commonly found in the breast and gums. Abscesses are far more serious and call for more specific treatment if they are located in deep organs such as the lung, liver, or brain.

Most abscesses are caused by an infection. In response to an invading germ, white blood cells gather at the infected site and begin producing chemicals called enzymes that attack the germ. These enzymes act like acid, killing the germs and breaking them down into small pieces to be picked up by the circulation and eliminated from the body. These chemicals also digest body tissues. In most cases, the germ produces similar chemicals. The result is a thick, yellow liquid--pus--containing digested germs, digested tissue, white blood cells, and enzymes.

Sterile abscesses are a milder form of the same process. They are not caused by germs but rather by non-living irritants such as drugs. If an injected drug like penicillin is not absorbed, it stays where it was injected and may cause enough irritation to generate a sterile abscess--sterile because there is no infection involved. Sterile abscesses are quite likely to turn into hard, solid lumps as they scar, rather than remaining pockets of pus.

Many different agents cause septic abscesses. The most common are the pus-forming (pyogenic) bacteria like Staphylococcus aureus, which are nearly always the cause of skin abscesses. Abscesses near the large bowel, particularly around the anus, may be caused by any of the numerous bacteria found within the large bowel. Brain and liver abscesses can be caused by any organism that can travel there through the circulation. Bacteria, amoeba, and certain fungi can travel in this fashion. Abscesses in other parts of the body are caused by organisms that normally inhabit nearby structures or that infect them.

An abscess can damage surrounding tissue. If an abscess ruptures into neighboring areas or permits the infectious agent to spill into the bloodstream, serious consequences may follow. Blood poisoning describes a local infection that has spilled into the blood stream and spread throughout the body. Blood poisoning, known to physicians as septicemia, is life threatening. Abscesses in and around the nasal sinuses, face, ears, and scalp may work their way into the brain. Abscesses within an abdominal organ such as the liver may rupture into the abdominal cavity with life-threatening results.

Superficial abscesses are easily identified by local inflammation. Deeper abscesses may produce symptoms such as fever and discomfort. If the patient's symptoms and physical examination do not help, a physician may have to do tests to locate an abscess. An imaging technique such as a computed tomography scan may be used to locate an abscess and confirm its size.

Some abscesses can be treated with antibiotics, but often the lining of the abscess cavity blocks the drug from getting to the source of infection. In this case, the cavity must be drained. A doctor will cut into the lining of the abscess, which allows pus to escape. Once the abscess is opened, the doctor cleans and irrigates the wound thoroughly with saline. If it is not too large or deep, the doctor may simply pack the abscess wound with gauze for 24-48 hours to absorb the pus and discharge. Most abscesses heal after drainage alone; others require drainage and antibiotic drug treatment.

If it is a deep abscess, the doctor may insert a drainage tube after cleaning out the abscess. Once the tube is in place, the surgeon closes the incision with simple stitches, and applies a sterile dressing. Drainage is maintained for several days to help prevent the abscess from reforming. Much of the pain around the abscess will be gone after the surgery. Healing is usually very fast. After the tube is taken out, antibiotics may be continued for several days.