The establishment of a Pseudomonas aeruginosa-infected burn-wound sepsis model and the effect of imipenem treatment

Introduction: We present a standardized Pseudomonas aeruginosa (PA) infected burn-wound model in mice for evaluating new anti-microbials and therapy strategies for PA infections and demonstrate the effect of the antibiotic imipenem in this model. Methods: A 6%-8% total body surface area, full-thickness, scald-burn wound was induced in anesthetized mice. Two study groups (PA-infected burn) were compared with 1 treatment group (systemic imipenem) and 3 control groups (noninfected burn, infected nonburned, and burn with distant infection). Seven-day mortality, quantitative culture from eschars and from spleens, weight loss, and time to healing were compared. Results: The 25%-100% mortality rate in the nontreated PA-infected burn group was directly related to the infecting inoculum. Imipenem treatment reduced the mortality rate to 0-17%. No control animal died. Systemic bacterial dissemination at 48 hours was significantly higher in the study group. Morbidity paralleled survival results. Wound healing was quicker in the imipenem-treated group and control groups compared with the infected nontreated group. Conclusions: The mice model is a useful tool for evaluating new antibacterial agents and strategies for treating PA-infected burn injuries. Imipenem was found to be efficacious in the treatment of severe PA sepsis.