Figure 7. P. aeruginosa biofilms on wound dressings delay wound healing.

P. aeruginosa biofilms with or without 10mM D-/L-tryptophan were established on wound dressings for 48 hours at 30°C. The contaminated dressings were applied to mouse skin wounds for up to 9 days. On days 3, 6, and 9, two mice from each group were sacrificed for imaging of the wounds, bacterial quantification of the dressing and wound bed. A) Representative images of the wounds in the three groups on days 0 and 9. B) Wound areas are expressed as percentages of the day 0 baseline (100%). By day 9 the control wounds without P. aeruginosa were ~50% closed, the biofilms grown in the presence of tryptophan were ~35% closed, and the biofilms grown without tryptophan remained fully open. C) Bacterial loads on the dressing (log₁₀ CFU/dressing) did not change significantly over the 9 days on the mouse skin wounds. D) Tryptophan slightly reduced the bacterial loads on the wound bed (log₁₀ CFU/g) with significantly lower counts detectible on day 9.