Evaluation of standard surgical preparation performed on superficial dermal abrasions

Objectives: To determine the difference, if any, between the reduction of b acteria on contaminated normal skin and contaminated superficially abraded skin following standard surgical preparations at clinically relevant time p oints after injury. Design: Prospective animal study. Setting: Laboratory. Subjects: Thirty-two New Zealand white rabbits. Intervention: Two sites, two by two centimeters, one abraded and one nonabr aded (control), were studied on each rabbit. Both were inoculated with enca psulated Staphylococcus aureus strain Wood 46. Four six-millimeter punch bi opsies were obtained after inoculation, immediately before surgical scrub, and five minutes and then two hours after completion of the surgical scrub. The rabbits were divided into four cohort groups with surgical scrubs perf ormed at six, twelve, twenty-four, and forty-eight hours after inoculation. Bacterial counts were determined. Main Outcome Measurements: Numbers of bacteria on surgical sites. Results: Before surgical preparation, the amount of bacteria on the normal skin (control sites) dropped significantly (p < 0.02) except in the six-hou r group (p < 0.20). At the abraded skin sites, the bacteria nourished. The surgical scrub dropped bacterial counts at both the abraded and nonabraded skin sites significantly (p < 0.05) except for the abraded site in the twen ty-four-hour group (p < 0.08), However in the twelve-, twenty-four-, and fo rty-eight-hour groups, the bacterial counts (colony-forming units) were sti ll markedly elevated (>1 X 10(5) at abraded sites) when compared with the n onabraded skin sites (p < 0.008) at the respective time intervals, Only at the six-hour interval were the bacterial counts reduced similarly at both t he abraded and nonabraded skin sites. Conclusions: in a rabbit model the standard surgical preparation using povi done-iodine at six hours after inoculation is effective in reducing the bac terial count on abraded skin to that of surgically prepared nonabraded skin . Beyond that time, the standard surgical preparation is ineffective in red ucing counts to those of nonabraded skin at similar time intervals.