definition

pus in the tissue, organ, interorgan, space, usually caused by a bacterial infection

pathogenesis

entry of microorganism a/ direct implantation (penetrating trauma), b/ propagation of existing infection to the surroundings, c/ dissemination via lymphatic/hematogenous pathways from a distant place, d/ migration from the place of resident flora to adjacent places, normally sterile places (by breaking natural barriers - intra-abdominal abscess after perforation)

predisposing factors

impaired defense mechanisms (eg leukocyte dysfunction), presence of foreign body, obstruction of normal drainage (urinary, biliary, respiratory tract), tissue ischemia/necrosis, hematoma/excessive fluid accumulation in the tissue, trauma

symptoms, signs

skin/subcutaneous abscess - (redness, increase in local/body temperature, swelling, tenderness, soreness), deep abscess - (pain, tenderness, fever, anorexia, weight loss, general weakness, abnormal organ function - eg hemiplegia in brain abscess)

complications

bacteremia with propagation of infection to distant sites, rupture of adjacent tissue, bleeding from vessels eroded by inflammation, impaired vital organ function, inanition from systemic effects of anorexia and tissue metabolism

therapy - principles

surgical evacuation and drainage, systemic antimicrobial drugs