Molecular Mechanisms Underlying Mucosal Attachment and Colonization by Clostridioides difficile

Authors

Ben Sidner, University of Nebraska-LincolnFollow

First Advisor

Dr. Kurt Piepenbrink

Second Advisor

Dr. Jennifer Auchtung

Third Advisor

Dr. Devin Rose

Date of this Version

Summer 7-2022

Comments

A THESIS Presented to the Faculty of The Graduate College at the University of Nebraska In Partial Fulfillment of Requirements For the Degree of Master of Science, Major: Food Science and Technology, Under the Supervision of Professor Kurt H. Piepenbrink. Lincoln, NE: July 2022

Copyright © 2022 Benjamin Sidner

Abstract

Clostridioides difficile is a Gram-positive, spore-forming, anaerobic bacterium which causes gastrointestinal disease and is a leading cause of nosocomial infections. Although infection typically occurs following antibiotic therapy, in recent years there has been an increase in infections which are not preceded by antibiotic use. Additionally, community-associated infections and rates of disease recurrence have increased. While it is understood that a healthy gastrointestinal microbiota provides protection against infection, the molecular mechanisms which underly C. difficile's ability to colonize and persist in the gut are mostly unknown. Building on work from others that suggests C. difficile associates with the outer mucus layer during infection, we utilized an in vitro mucus layer model to probe attachment and colonization mechanisms. Using gene-interruption mutants of the major subunits of type IV pili and flagella, two extracellular appendages implicated in adhesion, we observed that the presence of flagella facilitates initial mucus attachment. Adhesion was variable across multiple strains of C. difficile and was also dependent on the source of mucin derivation. When mucin glycans were modified by mucin-degrading bacteria, C. difficile attachment decreased in our model. Collectively, our findings suggest that adherence to mucin likely influences C. difficile's ability to colonize and may offer novel strategies for future therapeutics once the underlying mechanisms are better understood.

Advisor: Kurt H. Piepenbrink