Host-Opportunist Interactions in Surgical Infection

The incidence of infection is related to the severity of injury, and the occurrence of septic complications is influenced by the balance between host defense and microbial invasiveness. Interactions between the host and opportunistic organisms not only affect that balance, usually by exaggerating pathophysiologic abnormalities, and adversely influence patient outcome, but also confound the diagnosis of sepsis. Those host-opportunist interactions explain, at least inpart, some of the limitations of current managemern of surgical infections, and a consideration of their effects indicates ways in which we can address both clinical and research problems related to surgical infection. Host-opportunist interactions may occur either locally to affect events at the site of injury or systemically to affect remote tissues and organs. In the burn wound, the absence of local blood supply, characteristics of a full-thickness burn, significantly influences the risk of infection by preventing delivery of the components of the host defense system and similary the delivery of systemically administrated antibiotics. The ischemia of the eschar also permits proliferation of the microorganisms that invariably colonize a burn wound. Other local host factors that influence the incidence of infection include tissue pH acidosis predisposes to fungal infection as well as wound temperature and moisture content. The biochemical characteristics of the cells within a wound appear to influence the occurrence of certain burn wound infections.