In the brain, of course, they are much more likely to cause serious disease. Abscesses are localized infections typically caused by staphylococci, which have a tendency to produce pus and not to spread through tissue. Cysts which become infected may become abscesses. This is most common on the face, in the armpits and the inner thighs, but sebaceous cysts may become infected and turn into abscesses anywhere on the skin surface. Abscesses may also occur in other tissues and internal organs, but internal cysts, such as kidney or liver cysts, seldom become infected and therefore do not turn into abscesses.
Abscesses cause pain and often fever or other signs of localized infection.
They almost always require treatment, and will often require drainage. Internal abscesses usually have to be surgically removed or drained. Antibiotics alone are generally not effective in treating abscesses, since the antibiotic cannot easily diffuse into the pus of the abscess. In addition, staphylococci and other abscess-forming bacteria are increasingly resistant to most antibiotics. After an abscess has been drained, and a culture taken to see if the bacteria are sensitive, then an antibiotic may speed healing.