RESUMO
Nearly all open wounds are contaminated by microorganisms. This generally corresponds to simple bacterial growth, without leading to deleterious effects or compromising the progress of the healing process. In acute wounds, the probability of wound infection increases as the level of contamination does. However, it is more complex for chronic wounds, which are able to contain and tolerate large amounts of bacteria, many times higher than the usual threshold level (>105 bacteria/g of tissue) defining infection in acute wounds,1 without inducing local signs. Nevertheless, many clinical and experimental studies indicate that the probability for chronic wounds to heal properly is limited when the bacterial load exceeds this level of contamination; even when body defences are still able to prevent tissue invasion, bacteria can impair wound healing.