Antibiotic screening of medicinal plants of the British Columbian native peoples.

One hundred methanolic plant extracts, 96 of which had documented medicinal uses by British Columbian native peoples, were screened for antibiotic activity against 11 bacterial strains. Eighty-five percent were found to have significant antibiotic activity against at least two of the bacteria tested. Ninety-five percent of the plants categorized as potential antibiotics based on their ethnobotanical usage were found to exhibit significant antibiotic activity. Seventy-five were found to be active against methicillin-resistant Staphylococcus aureus, 46 were active against an antibiotic supersusceptible strain of Pseudomonas aeruginosa and 18 of these were also active against a wild type strain. The extracts with the broadest spectra of activity were prepared from: Alnus rubra bark and catkins, Fragaria chiloensis leaves, Moneses uniflora aerial parts, and Rhus glabra branches.