The effect of scrubbing and irrigation with normal saline, povidone iodine, and cefazolin on wound bacterial counts in a guinea pig model.

This study examines the effects of povidone iodine, normal saline, and cefazolin alone and after scrubbing on bacterial counts in contaminated animal lacerations. Twelve albino guinea pigs each received four lacerations inoculated with a standard inoculum of Staphylococcus aureus. Twelve hours after inoculation, each wound was biopsied to ensure contamination and then either treated or left as an untreated control. One wound on each animal was an untreated control. The remaining three lacerations on six pigs were irrigated with cefazolin (CZ) solution, normal saline, or 1% (wt/vol) povidone iodine solution (PI). Three lacerations on another six pigs were treated with 20% poloxamer 188 scrub (scrub) alone, scrub followed by PI irrigation (SCR/PI), or scrub followed by CZ irrigation (SCR/CZ). Quantitative bacteriology was performed on tissue biopsies 2 hours (time 1), 7 hours (time 2), and 12 hours (time 3) after irrigation. Posttreatment counts for PI, CZ, and normal saline irrigation were not different from control or one another (P > .05). Bacterial counts for SCR/PI were significantly lower than control (P < .05) for all posttreatment biopsies (1.8 to 2.9 mean log(10) decrease). SCR/CZ was significantly lower than control (P < .05) at times 2 and 3 only (1.7 to 2.0 mean log(10) decrease). In this guinea pig model, cleansing 12-hour-old lacerations contaminated with S aureus using SCR/PI or SCR/CZ significantly reduced bacterial counts over 12 hours.