Antimicrobial Activity of Bark from Four North American Tree Species.

Introduction: Although many backcountry first aid kits contain antibiotic ointment, the supply can be quickly exhausted if a patient has extensive wounds or if there are multiple patients.

Methods: We assessed the antibacterial properties of bark extract from four North American woody plant species known to native Missourians as medicinal plants (Quercus macrocarpa, Salix humilis, Pinus echinata, and Hamamelis vernalis). We tested their antimicrobial properties, with the disc diffusion technique, against four common pathogenic bacterial species: Klebsiella pneumoniae, Pseudomonas aeruginosa, Staphylococcus aureus, and Enterobacter aerogenes (now known as Klebsiella aerogenes).

Results: We report evidence of antibacterial activity of bark extract from all four plant species.

Conclusions: Our results confirm that traditional uses of these species may be useful in fighting infection and could be especially useful in a wilderness setting when modern antibiotics are exhausted.