 Probiotics are live microorganisms that are available over the counter, widely used as dietary supplements or nutritional foods and represent a low-cost, well tolerated, safe, non-antibiotic based strategy that may have efficacy for decolonization without the attendant risks of promoting antimicrobial resistance.9 Certain probiotics, including Lactobacillus rhamnosus HN001, have demonstrated ability to stimulate systemic immune functions, possibly enhancing the bodys ability to eradicate S. aureus in the gastrointestinal tract and at sites remote from the gastrointestinal tract such as the nose.10 ,11 The long-term goal of this research is to identify and test novel interventions for reducing infections caused by resistant bacteria. The investigators propose a Phase II randomized, double-blind, placebo-controlled clinical trial in Veterans to evaluate the efficacy of an oral probiotic, Lactobacillus rhamnosus HN001, for reducing S. aureus colonization. This study will produce data, methods, and tools that have widespread relevance and portability, with the potential to reduce healthcare-associated infections. 