Egress of Listeria monocytogenes from Mesenteric Lymph Nodes Depends on Intracellular Replication and Cell-to-Cell Spread

Abstract

The mesenteric lymph nodes (MLN) function as a barrier to systemic spread for both commensal and pathogenic bacteria in the gut. Listeria monocytogenes , a facultative intracellular foodborne pathogen, readily overcomes this barrier and spreads into the bloodstream, causing life-threatening systemic infections. We show here that intracellular replication protected L. monocytogenes from clearance by monocytes and neutrophils and promoted colonization of the small intestine-draining MLN (sMLN) but was not required for dissemination to the colon-draining MLN (cMLN).