Increased susceptibility to infection related to extent of burn injury.

A model of burn wound sepsis in which the mortality caused by infection was significantly greater after a 60% total body surface area (TBSA) burn than after a 30% TBSA burn was developed in the rat. In rats that sustained a 60% TBSA burn (30% partial plus 30% full thickness), the 30% TBSA partial-thickness burn that was inoculated with Pseudomonas aeruginosa strain 59-1244 developed invasive wound infection (greater 10(5) colony-forming units per gram of tissue). Infection did not develop in rats that had a 30% TBSA partial-thickness burn inoculated, without additional injury. The additional burn in the rats with a 60% TBSA burn seemed to affect the development of infection in the partial-thickness wound and the overall outcome by a mechanism other than by infection of the full-thickness wound itself. Autopsy confirmed that mortality was caused by sepsis.