An abscess is an infection caused by bacteria (Staphylococcus aureus) under the skin, which is very painful leading to formation of pus. The bacteria find its way through cracked breast skin or the nipple, resulting in an infection, called mastitis. The bacteria infect the fatty tissue of the breast, causing swelling and pressure on the milk ducts, resulting in pus formation. The pus from the infected milk ducts gets filled in the hollow space in the breast, forming an abscess.
Breast abscesses usually affects lactating women – ones producing milk or who breast feed. It may also afflict women aged between 18 and 50 years. In women who are not lactating, the presence of an abscess may be a symptom of new-onset diabetes or an uncommon type of inflammatory cancer. In rare cases, if the infection spreads in blood stream, an abscess can lead to severe consequences such as a whole body infection (sepsis, a life-threatening bacterial blood infection).