Stress-induced susceptibility to bacterial infection during cutaneous wound healing

Psychological stress delays wound healing and decreases immune/inflammatory responses required for bacterial clearance. To determine if stress increases the susceptibility to wound infection, female SKH-1 mice were subjected to restraint stress (RST) beginning 3 days prior to the placement of cutaneous wounds. Viable bacteria were quantified from harvested wounds. RST delayed healing by 30% and caused a 2- to 5-log increase in opportunistic bacteria (e.g., Staphylococcus aureus) when compared to wounds from control animals (p < .05). By day 7, 85.4% of the wounds from RST mice had bacterial counts predictive of infection compared to 27.4% from control mice (p < .001). To assess the role of RST-induced glucocorticoids in bacterial clearance, mice were treated with the glucocorticoid receptor antagonist RU486. RU486 reduced opportunistic bacteria by nearly 1 log in wounds from RST mice (p < .05). Thus, stress impairs bacterial clearance during wound healing, resulting in a significant increase in the incidence of opportunistic infection.