1. Department of Microbiology, University of Minnesota Medical School, 420 Delaware Street SE, Minneapolis, Minnesota 55455, Department of Experimental and Clinical Pharmacology, University of Minnesota College of Pharmacy, 308 Harvard Street, SE, Minneapolis, Minnesota 55455, The Procter & Gamble Company, 6110 Center Hill Road, Cincinnati, Ohio 45224, and The Procter & Gamble Company, 11810 East Miami River Road, Ross, Ohio 45252