Inflammatory Reaction and Blood Flow in Experimental Wounds Inoculated with <i>Staphylococcus aureus</i>

Abstract

Wound healing and granulation tissue fromation can be accelerated by inoculation with live pathogenic microorganisms. For further elucidation of this phenomenon the present work was undertaken to study the effects of Staphylococcus aureus microorganisms on the inflammatory reaction and blood flow in developing granulation tissue in rats. Cylindrical hollow sponge implants were used as an inductive matrix for the growth of granulation tissue. In control animals 1 ml of wound fluid was withdrawn from the central dead space of the implant immediately after implantation and replaced with 1 ml of physiological saline. In experimental animals the implants were injected with live staphylococci, 10² or 10⁵ microorganisms/ml. Wound fluid was analyzed 3, 7, 10 and 14 days after implantation, whereas measurements of local blood flow and albumin extravasation in the granulation tissue were made after 7 days. Implants inoculated with 10⁵ organisms developed infection with pus formation while implants contaminated with 10² organisms showed no infection. In wound fluid specimens collected from the infected implants correlation between the number of polymorphonuclear leukocytes and prostaglandin E₂ concentration was statistically significant. The most prominent finding in contaminated but uninfected implants was an enhanced local blood flow. This may explain some of the mechanisms leading to S. aureus-induced acceleration of wound healing.

The Effect of pH on the Extracellular Matrix and Biofilms

“…Some researchers have found that very low levels of bacteria in fact accelerate wound healing and the formation of granulation tissue. 42 However, an increase in bacterial load within a wound has the opposite effect. An increase in the production of bacterial enzymes results in excess granulation tissue and scar formation.…”

Treating the chronic wound: A practical approach to the care of nonhealing wounds and wound care dressings

“…69 In some instances, colonization may actually hasten wound healing by increasing wound bed perfusion. 70,71 At the point of critical colonization, however, host defenses can no longer maintain this balance and the wound may enter a nonhealing, chronic inflammatory state. 69 Bacterial loads in excess of 10 5 organisms per gram of tissue are said to impede wound healing, though the status of the host immune system and the number and types of bacterial species present may alter this threshold.…”

Effects of low intensity laser irradiation during healing of infected skin wounds in the rat

“…Wound colonization at low concentration (<10 5 organisms per gram of tissue) will usually not impede wound healing as long as host resistance and bacterial activity remain in balance. In fact, bacterial presence at low concentration may stimulate granulation tissue formation thereby improving healing [14,15]. Further, by binding to available receptor sites on the wound surface, normal flora protect wounds from colonization by environmental organisms that are potentially more dangerous, for example, Staphylococcus aureus and Pseudomonas aeruginosa.…”