Bacterial resistance to antibiotics is a growing concern to society and treatments require the discovery of new antimicrobial compounds. This study evaluated fourteen different edible and/or medicinal mushroom species for antimicrobial activity. Growth inhibition of Saccharomyces cerevisiae, and of ciprofloxacin-resistant strains of Escherichia coli was examined using bioassays and by Minimum Inhibitory Concentration with alcohol extracts of mushroom mycelia and culture broth. Cultures used for extract preparations were grown in Potato Dextrose Broth with or without induction using a) low-nutrient medium, b) spent Escherichia coli filtrate, or c) 5-azacytidine. Several extracts resulted in a reduction in bacterial and/or yeast growth, although full inhibition was observed with only a few extracts. Fungi with antimicrobial activity may be useful as a food therapy as well as leads in drug discovery and this study confirms that basidiomycetes may provide new, useful antimicrobials.