Pathophysiology of infection--a theoretical approach

The manifestation of postoperative wound infection has a tri-factorial basis: the overall systemic trauma and the additional effects of premorbidity (age, diabetes, etc.), the local host damage resulting from both the accident and surgery, and the bacterial contamination of the wound. The first factor is only moderately open to intervention, however, the amount of local host damage caused during the operation can be influenced directly by the surgeon who must ensure that his operating techniques are non-aggressive and in line with current knowledge. The factor of the intraoperative bacterial inoculum can be modified by attention to hygiene. The latter two factors are in direct relation to the following two hypotheses: Every wound is able to tolerate some local host damage and some bacterial inoculum without manifestation of infection. The bacterial wound flora is the product of the bacterial invasion force and the local wound conditions. The bacterial wound flora and the local condition of the wound are interrelated. If either factor exceeds the tolerable threshold, infection will become manifest, i.e. there will be an uncontrollable proliferation of bacteria. The level of this breaking point may depend upon certain systemic host factors such as age, diabetes, or immunodeficiency. Consequently, the prevention of infection must focus simultaneously on minimizing the local bacterial inoculum and optimizing local wound conditions. Future studies should concentrate on identifying the exact nature of the individual factors promoting infection, their quantification, and their relative importance.