Life Sciences Commons^™

Protection From Staphylococcus Aureus Bloodstream Infection By Probiotic Exopolysaccharide, Wonbeom Paik

Dissertations

Staphylococcus aureus is known to cause severe systemic infection with high mortality rates. Antibiotics are the only approved therapy for patients, but the widespread prevalence of antibiotic resistant strains limits treatment efficacy, and many patients succumb to the disease. Many probiotic agents are commercially available, but the mechanisms by which they benefit are not known. Understanding these mechanisms will help develop novel therapeutics that can improve healthcare, including systemic infections by S. aureus. Bacillus subtilis is a probiotic bacterium that produces an exopolysaccharide (EPS) that induces anti inflammatory macrophages (MΦ). We tested if EPS could be used for systemic S. …

Mechanism By Which Commensal Bacteria Limit Inflammation, Mallory Paynich

Dissertations

Trillions of bacteria live within the gastrointestinal tract and are critical for maintaining intestinal homeostasis; however, the mechanisms utilized by specific bacterial molecules to contribute to homeostasis are not well understood. We utilize a mouse model in which a single oral dose of the probiotic, Bacillus subtilis, protects mice from acute colitis induced by the enteric pathogen Citrobacter rodentium. Our goal is to elucidate the mechanism by which B. subtilis prevents inflammation.

We identified exopolysaccharides (EPS) to be the active molecule of B. subtilis, and a single dose of EPS protects mice from disease. EPS binds F4/80+CD11b+ peritoneal macrophages, and …