Abscess is a collection of pus that has built up within the tissue of the body. Pus is a thick fluid that usually contains white blood cells, dead tissue and bacteria. The pus may be yellow or green and may have a bad smell. Signs and symptoms of abscesses include redness, pain, warmth, and swelling. The swelling may feel fluid filled when pressed. The area of redness often extends beyond the swelling.
Abscesses are usually caused by bacterial infection. When our normal skin barrier is broken, even from minor trauma, bacteria can enter the skin. In the US and many other areas of the world they are usually caused by methicillin-resistant Staphylococcus aureus and Streptococcus pyogenes. Some abscesses can be caused by parasites, but these are more common in the developing world. A major risk factor for developing skin abscesses is a weak immune system (either from chronic diseases or from medications), because the body’s ability to fight infection is decreased. Other risk factors include exposure to dirty environments or other people with infections, poor personal hygiene and poor circulation.