Staphylococcus aureus infections

[Dorothey Allen]

Staphylococcus aureus is the most dangerous of all of the many common staphylococcal bacteria. These gram-positive, sphere-shaped (coccal) bacteria (see figure How Bacteria Shape Up) often cause skin infections but can cause pneumonia, heart valve infections, and bone infections.

These bacteria are spread by having direct contact with an infected person, by using a contaminated object, or by inhaling infected droplets dispersed by sneezing or coughing.
Skin infections are common, but the bacteria can spread through the bloodstream and infect distant organs.
Skin infections may cause blisters, abscesses, and redness and swelling in the infected area.
The diagnosis is based on the appearance of the skin or identification of the bacteria in a sample of the infected material.
Thoroughly washing the hands can help prevent spread of infection.
Antibiotics are chosen based on whether they are likely to be effective against the strain causing the infection.

(See also Overview of Bacteria.)
Staphylococcus aureus is present in the nose (usually temporarily) of about 30% of healthy adults and on the skin of about 20%. The percentages are higher for people who are patients in a hospital or who work there.
The bacteria can spread from person to person by direct contact, through contaminated objects (such as gym equipment, telephones, door knobs, television remote controls, or elevator buttons), or, less often, by inhalation of infected droplets dispersed by sneezing or coughing.
Carriers are people who have the bacteria but do not have any symptoms caused by the bacteria. Carriers can move the bacteria from their nose to other body parts with their hands, sometimes leading to infection. People who are hospitalized or work in a hospital are more likely to be carriers.