Abscess

Abscesses may occur in any kind of tissue but most frequently within the skin surface (where they may be superficial pustules known as boils or deep skin abscesses), in the lungs, brain, teeth, kidneys, and tonsils. Major complications may include 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. An internal abscess is more difficult to identify and depends on the location of the abscess and the type of infection. General signs include pain in the affected area, a high temperature, and generally feeling unwell. ==Causes==

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, particularly Staphylococcus aureus. The more invasive methicillin-resistant Staphylococcus aureus (MRSA) may also be a source of infection, though it is much rarer. Among spinal subdural abscesses, methicillin-sensitive S. aureus is the most common organism involved. Skin abscess An abscess may form anywhere that bacteria can get through the skin, including insect bites, lacerations, puncture wounds, scrapes, IV injection sites, and other small surface-level injuries. The overwhelming majority of skin abscesses are caused by Staphylococcus aureus (methicillin-susceptible or methicillin-resistant) with some studies showing over 90% of documented and cultured skin abscesses being caused by this organism. Incisional abscess An incisional abscess develops as a complication secondary to a surgical incision. It presents as redness and warmth at the margins of the incision with purulent drainage from it. If the diagnosis is uncertain, the wound should be aspirated with a needle, with aspiration of pus confirming the diagnosis and availing for Gram stain and bacterial culture. ==Pathophysiology==

An abscess is a buildup of pus surrounded by normal body tissue. In most cases, abscesses are caused by an infectious species of bacteria, and they function to wall off the infection from uninfected tissues. Organisms or foreign materials destroy the local cells, which results in the release of cytokines. The cytokines trigger an inflammatory response, which draws large numbers of white blood cells to the area and increases the regional blood flow. The final structure of the abscess is an abscess wall, or capsule, that is formed by the adjacent healthy cells in an attempt to keep the pus from infecting neighboring structures. However, such encapsulation tends to prevent immune cells from attacking bacteria in the pus, or from reaching the causative organism or foreign object. File:Blausen 0007 Abscess.png|A diagram of an abscess file:Pyemic abscesses of kidney.jpg|Pyemic abscesses of a kidney ==Diagnosis==

An abscess is a localized collection of pus (purulent inflammatory tissue) caused by suppuration buried in a tissue, an organ, or a confined space, lined by the pyogenic membrane. Ultrasound imaging can help in a diagnosis. Classification Abscesses may be classified as either skin abscesses or internal abscesses. Skin abscesses are common; internal abscesses tend to be harder to diagnose and more serious. Skin abscesses are also called cutaneous or subcutaneous abscesses. IV drug use For those with a history of intravenous drug use, an X-ray is recommended before treatment to verify that no needle fragments are present. Other conditions that can cause similar symptoms include: cellulitis, a sebaceous cyst, and necrotising fasciitis. Cellulitis typically also has an erythematous reaction, but does not confer any purulent drainage. ==Treatment==

The standard treatment for an uncomplicated skin or soft tissue abscess is the act of opening and draining. In most cases, a localized injection of lidocaine and epinephrine precedes the incision, to suppress pain. Antibiotics Most people who have an uncomplicated skin abscess should not use antibiotics. Loop drainage More recently, several North American hospitals have opted for less-invasive loop drainage over standard drainage and wound packing. In one study of 143 pediatric outcomes, a failure rate of 1.4% was reported in the loop group versus 10.5% in the packing group (P<.030), while a separate study reported a 5.5% failure rate among the loop group. Primary closure Closing an abscess immediately after draining it appears to speed healing without increasing the risk of recurrence. Appendiceal abscess Appendiceal abscesses are complications of appendicitis, where there is an infected mass on the appendix. This condition is estimated to occur in 2–10% of appendicitis cases and is usually treated by surgical removal of the appendix (appendicectomy). ==Prognosis==

Even without treatment, skin abscesses rarely result in death, as they will naturally break through the skin. ==Epidemiology==

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 for the disease. ==Society and culture==

The Latin medical aphorism "ubi pus, ibi evacua" expresses "where there is pus, there evacuate it" and is classical advice in the culture of Western medicine. Needle exchange programmes often administer or provide referrals for abscess treatment to injection drug users as part of a harm reduction public health strategy. Etymology An abscess is so called "abscess" because there is an abscessus (a going away or departure) of portions of the animal tissue from each other to make room for the suppurated matter lodged between them. The word carbuncle is believed to have originated from the Latin: carbunculus, originally a small coal; diminutive of carbon-, carbo: charcoal or ember, but also a carbuncle stone, "precious stones of a red or fiery colour", usually garnets. ==Other types==

The following types of abscess are listed in the medical dictionary: == References ==