Intracellular Listeria monocytogenes comprises a minimal but vital fraction of the intestinal burden following foodborne infection

Grant S. Jones, Kate M. Bussell, Tanya Myers-Morales, Abigail M. Fieldhouse, Elsa N. Bou Ghanem, Sarah E.F. D'Orazio

Research output: Contribution to journalArticlepeer-review

26 Scopus citations


Listeria monocytogenes is a highly adaptive bacterium that replicates as a free-living saprophyte in the environment as well as a facultative intracellular pathogen that causes invasive foodborne infections. The intracellular life cycle of L. monocytogenes is considered to be its primary virulence determinant during mammalian infection; however, the proportion of L. monocytogenes that is intracellular in vivo has not been studied extensively. In this report, we demonstrate that the majority of wild-type (strain EGDe) and mouse-adapted (InlAm-expressing) L. monocytogenes recovered from the mesenteric lymph nodes (MLN) was extracellular within the first few days after foodborne infection. In addition, significantly lower burdens of L. monocytogenes were recovered from the colon, spleen, and liver of gentamicin-treated mice than of control mice. This led us to investigate whether intracellular replication of L. monocytogenes was essential during the intestinal phase of infection. We found that lipoate protein ligase-deficient L. monocytogenes (ΔlplA1) mutants, which display impaired intracellular growth, were able to colonize the colon but did not persist efficiently and had a significant defect in spreading to the MLN, spleen, and liver. Together, these data indicate that the majority of the L. monocytogenes burden in the gastrointestinal tract is extracellular, but the small proportion of intracellular L. monocytogenes is essential for dissemination to the MLN and systemic organs.

Original languageEnglish
Pages (from-to)3146-3156
Number of pages11
JournalInfection and Immunity
Issue number8
StatePublished - 2015

Bibliographical note

Publisher Copyright:
© 2015, American Society for Microbiology.

ASJC Scopus subject areas

  • Parasitology
  • Microbiology
  • Immunology
  • Infectious Diseases


Dive into the research topics of 'Intracellular Listeria monocytogenes comprises a minimal but vital fraction of the intestinal burden following foodborne infection'. Together they form a unique fingerprint.

Cite this