Eastern Pennsylvania Branch – American Society for Microbiology

770th Monthly Meeting
Monday, April 29, 2019

“Salmonella-Microbiome Interactions in the Gut and their Impact on Transmission”

Denise Monack, Ph.D.
Professor of Microbiology and Immunology
Stanford University School of Medicine

The Monack Laboratory 

Disease transmission is mediated by the interactions between the pathogen and host. Salmonella enterica serovars are important human enteric pathogens that cause disease ranging from self-limiting gastroenteritis to persistent systemic infections, such as typhoid fever.  Transmission occurs via the fecal-oral route, and epidemiologic analysis have revealed heterogeneity in host trasmissions capabilities. The underlying mechanisms that lead to this heterogeneity is an area of intense study.

Dr. Monack’s lab explores the dynamic interactions between Salmonella and the high-density polymicrobial community, the microbiota, in the distal gut. For example, the ability of Salmonella to colonize and grow in the lumen of the gut requires a type 6 secretion system (T6SS) which is encoded on a pathogenicity island.  Salmonellautilizes the T6SS to inject a lethal toxin into a commensal bacterium, Klebsiellaoxytoca, thus, eliminating a potential competitor.

Her laboratory also studies the mechanisms by which the intestinal microbiota provides protection against Salmonella.  Mechanisms of microbiota-mediated colonization resistance have been identified by observing loss of colonization resistance after community perturbations such as antibiotic treatment or diet changes.  Dr. Monack will describe a new microbiota-mediated mechanism of colonization resistance against Salmonella Typhimurium.  In particular, she will demonstrate that species mediate colonization resistance against S. Typhimurium in vivo through the production of short-chain fatty acid propionate, which directly inhibits S. Typhimurium growth in vitro by disrupting intracellular pH homeostasis.  Dr. Monak will provide the first mechanistic understanding of the role of individualized microbial communities in host-to-host variability of pathogen transmission. 

5:00 pm Reception
6:00 pm Seminar

Thomas Jefferson University
Bluemle Life Sciences Bldg Room 101
233 S. 10th Street (10th and Locust St)
Philadelphia, PA 19104

(discounted parking at the garage on 11th and Locust St, entrance on 11th Street under the Hamilton Bldg)