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Overview of Bacterial Skin Infections

by A. Damian Dhar, MD, JD

The skin provides a remarkably good barrier against bacterial infections. Although many bacteria come in contact with or reside on the skin, they are normally unable to establish an infection. When bacterial skin infections do occur, they can range in size from a tiny spot to the entire body surface. They can range in seriousness as well, from harmless to life threatening.

Many types of bacteria can infect the skin. The most common are Staphylococcus and Streptococcus. Skin infections caused by less common bacteria may develop in people while hospitalized or living in a nursing home, while gardening, or while swimming in a pond, lake, or ocean.

Some people are at particular risk of developing skin infections. For example, people with diabetes are likely to have poor blood flow, especially to the hands and feet, and the high levels of sugar (glucose) in their blood decrease the ability of white blood cells to fight infections. People who are older, who have human immunodeficiency virus (HIV) or AIDS or other immune disorders, or hepatitis, and who are undergoing chemotherapy or treatment with other drugs that suppress the immune system are at higher risk as well because they have a weakened immune system. Skin that is inflamed or damaged by sunburn, scratching, or other trauma is more likely to become infected. In fact, any break in the skin predisposes a person to infection.

Prevention involves keeping the skin undamaged and clean. When the skin is cut or scraped, the injury should be washed with soap and water and covered with a sterile bandage. Petrolatum may be applied to open areas to keep the tissue moist and to try to prevent bacterial invasion. Doctors recommend that people do not use antibiotic ointments (prescription or nonprescription) on uninfected minor wounds because of the risk of developing an allergy to the antibiotic. However, an antibiotic ointment is used if an infection develops. Larger areas require antibiotics taken by mouth or given by injection. Abscesses (pus-filled pockets) should be cut open by the doctor and allowed to drain, and any dead tissue must be surgically removed.