An abscess is a collection of pus (dead neutrophils and necrotic tissue) that has accumulated in a cavity formed by the destruction of tissue in which the pus resides. This is usually due to an infectious process or a reaction to a foreign body (e.g., splinters, bullets). It is the bodies defensive reaction to prevent the spread of infectious materials to other parts of the body. 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. This encapsulation prevents immune cells from attacking bacteria in the pus, or from reaching the causative organism or foreign object. Wound abscesses cannot be treated with antibiotics. They require surgical intervention, debridement and drainage.