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Overview of Bacterial Skin Infections

By A. Damian Dhar, MD, JD, Private Practice, North Atlanta Dermatology

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.

Classification and Causes

Because most of these infections involve skin and the tissues under the skin, they are formally classified as skin and soft tissue infections (SSTI), which include relatively minor infections such as

More serious infections, which are now called acute bacterial skin and skin structure infections (ABSSSI), include

Many types of bacteria can infect the skin. The most common are Staphylococcus and Streptococcus. Methicillin-resistant Staphylococcus aureus (also known as MRSA) is now the most common pathogen causing skin infections in the United States. One particular strain of MRSA is responsible for more than half of all community-associated skin and soft tissue infections treated in the United States. Because MRSA is resistant to several antibiotics, doctors tailor their treatment based on how often MRSA is found in the local area and whether or not it has been found to be resistant to commonly used antibiotics. 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.

Risk Factors

Some people are at particular risk of developing skin infections:

  • People with diabetes, who are likely to have poor blood flow, especially to the hands and feet, and the high levels of sugar (glucose) in their blood, which decrease the ability of white blood cells to fight infections

  • People who are older

  • People who have human immunodeficiency virus (HIV), AIDS or other immune disorders, or hepatitis

  • People who are undergoing chemotherapy or treatment with other drugs that suppress the 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 and Treatment

Preventing bacterial skin infections 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.