Clean Shot: Bacterial Contamination After Positive Pressure Irrigation of Low-Velocity Gunshot Wounds.

Objective: Low-velocity gunshot wounds (LV-GSWs) are a common reason for emergency department visits. Optimal nonsurgical treatment has not been thoroughly studied and is not standardized. The goal of this study was to determine whether positive pressure irrigation reduces the bacterial contamination after a simulated GSW to soft tissue.

Methods: Nineteen lamb shank specimens were prepared with denim inoculated with Serratia marcescens cultures. A 9-mm pistol round was fired from a distance of 3 m through the contaminated denim into the lamb shank. A culture swab was placed in the wound directly after firing, after 250 cubic-centimeters (cc) irrigation with normal saline, and after an additional 250 cc irrigation (for a total of 500 cc). Swabs were then cultured to determine the amount of bacterial growth.

Results: Before irrigation, 0 (0%) plates showed no growth, 2 (10.5%) showed rare growth, 8 (42.1%) showed few growth, 6 (31.6%) showed moderate growth, and 3 (15.8%) showed many growth. After 500 cc irrigation, 2 (10.5%) showed no growth, 1 (5.3%) showed rare growth, 11 (57.9%) showed few growth, 2 (10.5%) showed moderate growth, and 3 (15.8%) showed many growth. Fisher exact test confirmed no significant change in bacterial concentration after irrigation ( P = 0.59). A Pearson test found no correlation between irrigation and bacterial growth (r = -0.15, P = -0.25).

Conclusions: Positive pressure irrigation with up to 500 cc normal saline did not significantly alter the quantity of bacterial growth within a simulated GSW cavity. The data suggest that bedside positive pressure irrigation may not be beneficial in the initial emergency department treatment of LV-GSWs.