Many microorganisms reside in our bodies as part of normal living. For example, bacteria in the gastrointestinal system outnumber our own cells and form a stable connection with the body that persists for life. These resident bacteria are needed for parts of the digestive tract to develop and function properly. In addition, beneficial bacteria attach to the walls of the intestinal tract, preventing harmful bacteria from occupying these surfaces, and protect us from infectious diseases as a result. A lot of research has focused on disease-causing bacteria like E. coli and Salmonella, which are among the leading causes of gastrointestinal illness and death worldwide. Yet little is known about the role of beneficial bacteria in battling these microbes, which is the focus of Inna Sekirov’s research. She is examining what role resident bacteria play during the response of the intestinal immune system to infection and how these bacteria respond to antibiotics used to treat gastrointestinal illnesses. Findings from her research will help to establish whether drugs are likely to have a positive or adverse impact on a patient’s beneficial bacteria, and could also help inform new therapies or dietary regimes that complement or strengthen the ability of these bacteria to help the body fight infection.