Staphylococcal Infections Health Article

Definition

Staphylococcal (staph) infections are communicable diseases caused by various species of staphylococcal bacteria and are generally characterized by the formation of abscesses. They are the leading cause of nosocomial infections (infections originating in hospitals) in the United States.

Description

Classified since the early twentieth century as among the deadliest of all disease-causing organisms, staph exists on the skin or inside the nostrils of 20% to 30% of healthy people. It is sometimes found in breast tissue and the mouth, as well as the genital, urinary, and upper respiratory tracts.

Although staph bacteria are usually harmless, when injury or a break in the skin enables the organisms to invade the body, consequences can range from minor discomfort to death. Infection is most likely to occur in:

• newborns
• women who are breastfeeding
• individuals whose immune systems have been compromised by radiation treatment, chemotherapy, or medication
• intravenous drug users
• patients with surgical incisions, skin disorders, and serious illness such as cancer, diabetes, and lung disease

Types of infections

Staph infections produce pus-filled abscesses located just beneath the surface of the skin or deep within the body. Risk of infection is greatest among the very young and the very old.

A localized staph infection is confined to a ring of dead and dying white blood cells and bacteria. The skin above it feels warm to the touch. Most of these abscesses eventually burst, and pus that leaks onto the skin can cause new infections.

A small fraction of localized staph infections enter the bloodstream and spread through the body. In children, these systemic (affecting the whole body) or disseminated infections frequently affect the ends of the long bones of the arms or legs, causing a bone infection called osteomyelitis. When adults develop disseminated staph infections, bacteria are most apt to infect the brain, heart, kidneys, liver, lungs, or spleen.

There are three staphylococcal species that commonly cause infections: Staphylococcus aureus, Staphylococcus epidermidis, and Staphylococcus saprophyticus.