Bacterial Skin Infections
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

Impetigo

Minor skin abscesses (sometimes called furuncles and carbuncles)

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

Cellulitis

Erysipelas

Wound infections

Major skin abscesses (larger than 75 cm2 accompanied by swelling, redness, and hardening and thickening of the skin)

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.