Abscess

An abscess is a collection of pus that has built up within the tissue of the body. 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. Carbuncles and boils are types of abscess that often involve hair follicles, with carbuncles being larger.A diagram of an abscessPyemic abscesses of kidney An abscess is a collection of pus that has built up within the tissue of the body. 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. Carbuncles and boils are types of abscess that often involve hair follicles, with carbuncles being larger. They are usually caused by a bacterial infection. Often many different types of bacteria are involved in a single infection. In the United States and many other areas of the world the most common bacteria present is methicillin-resistant Staphylococcus aureus. Rarely, parasites can cause abscesses; this is more common in the developing world. Diagnosis of a skin abscess is usually made based on what it looks like and is confirmed by cutting it open. Ultrasound imaging may be useful in cases in which the diagnosis is not clear. In abscesses around the anus, computer tomography (CT) may be important to look for deeper infection. Standard treatment for most skin or soft tissue abscesses is cutting it open and drainage. There appears to be some benefit from also using antibiotics. A small amount of evidence supports not packing the cavity that remains with gauze after drainage. Closing this cavity right after draining it rather than leaving it open may speed healing without increasing the risk of the abscess returning. Sucking out the pus with a needle is often not sufficient. Skin abscesses are common and have become more common in recent years. Risk factors include intravenous drug use, with rates reported as high as 65% among users. In 2005 in the United States, 3.2 million people went to the emergency department for an abscess. In Australia, around 13,000 people were hospitalized in 2008 with the condition. Abscesses may occur in any kind of tissue but most frequently on skin surface (where they may be superficial pustules (boils) or deep skin abscesses), in the lungs, brain, teeth, kidneys, and tonsils. Major complications are spreading of the abscess material to adjacent or remote tissues, and extensive regional tissue death (gangrene). The main symptoms and signs of a skin abscess are redness, heat, swelling, pain, and loss of function. There may also be high temperature (fever) and chills. If superficial, abscesses may be fluctuant when palpated; this wave-like motion is caused by movement of the pus inside the abscess. An internal abscess is more difficult to identify, but signs include pain in the affected area, a high temperature, and generally feeling unwell.Internal abscesses rarely heal themselves, so prompt medical attention is indicated if such an abscess is suspected. An abscess can potentially be fatal depending on where it is located. Risk factors for abscess formation include intravenous drug use. Another possible risk factor is a prior history of disc herniation or other spinal abnormality, though this has not been proven. Abscesses are caused by bacterial infection, parasites, or foreign substances.Bacterial infection is the most common cause. Often many different types of bacteria are involved in a single infection. In the United States and many other areas of the world the most common bacteria present is methicillin-resistant Staphylococcus aureus. Among spinal subdural abscesses, methicillin-sensitive Staphylococcus aureus is the most common organism involved.