The skin of human beings naturally harbors many different types of bacteria that are potentially harmful and can cause skin infections. Typically, infection only occurs when the immune system is not functioning at full capacity. Bacteria that cause these infections, known as opportunistic pathogens, take advantage of the lack of immune function, causing skin infections.
Normal Flora
According to Dr. Kenneth Todar, bacteria that make up the normal flora of the skin include Staphylococcus epidermidis, Staphylococcus aureus, Streptococcus pyogenes, Corynebacteria and Mycobacteria. The normal flora, bacteria that live on the skin as part of their normal growth and life cycle, may change depending on the external environment. Extremely hot or cold environments can kill off bacteria living on the surface of the skin.
Cause of Infection
Typically, humans coexist with normal skin flora bacteria every day in a mutually advantageous situation. The bacteria get nutrients for growth from the skin, and the skin is protected from much more harmful bacteria that may be present in the environment. The normal flora bacteria can out-compete potentially more invasive bacteria for nutrients, reducing the chance of a major infection. However, normal flora bacteria can cause infection when the opportunity presents itself. If an individual has a cold, open wound or some other chronic condition, and the immune system is taking care of that problem, opportunistic skin bacteria can use this chance to infect you.
Skin Conditions
The University of Maryland Medical Center describes bacterial skin infections such as cellulitis, folliculitis, erysipelas, erythrasma, impetigo and paronychia as resulting from normal skin flora bacteria.
Symptoms
The first signs of a skin infection due to bacteria will often include redness and/or soreness in the infected area. Swelling of the area will follow in certain cases, and the area of the skin may feel warm. Advanced symptoms may include pus-filled boils or blisters.
Treatment
Treatment of a skin infection can vary depending on the severity. A doctor may swab the skin in the infected area in an attempt to determine what type of bacteria caused the infection. Severe skin infections will likely be prescribed a course of antibiotics. Depending on the antibiotic, the bacteria will either stop growing or be killed off entirely. If the infection is not serious, the doctor may choose not to use antibiotics. The overuse of antibiotics has rendered many of them ineffective against problems such as skin infections. Dressing the infected area and waiting for the immune system to do its job may be just as effective as antibiotic use.
Non-Typical Cases
While the vast majority of infections of the skin occur due to normal flora bacteria, some bacteria that do not normally reside on the skin can cause serious infection in the immunocompromised individual. Methicillin-resistant Staphylococcus aureus, or MRSA, does not typically live on the skin. This especially harmful bacteria is not killed by normally used antibiotics and is especially hard to treat. It is often picked up in a hospital environment.
