In episode 51 of MicrobeWorld Video, filmed at the American Association for the Advancement of Science Meeting in Washington, D.C., on February 18, 2011, Dr. Stan Maloy talks with David Relman, M.D., Thomas M. and Joan C. Merigan Professor, Department of Medicine - Division of Infectious Diseases, and Department of Microbiology & Immunology in the Stanford University School of Medicine.Maloy and Relman discuss microbial flora in the mouth and gut and why they are important for human health. They explore the impact of antibiotics and probiotics on the community of microbes in the gut and their health implications both negative and positive. Lastly they look at the future of probiotics in personalized medicine and the potential for individualized treatment based on the uniqueness of a person's gut flora.