Gastrointestinal Tract Colonization Dynamics by Different Enterococcus faecium Clades

Maria Camila Montealegre, Kavindra V. Singh, Barbara E. Murray

Research output: Contribution to journalArticlepeer-review

37 Scopus citations


Colonization of the gastrointestinal tract (GIT) generally precedes infection with antibiotic-resistant Enterococcus faecium. We used a mouse GIT colonization model to test differences in the colonization levels by strains from different E. faecium lineages: clade B, part of the healthy human microbiota; subclade A1, associated with infections; and subclade A2, primarily associated with animals. After mono-inoculation, there was no significant difference in colonization (measured as the geometric mean number of colony-forming units per gram) by the E. faecium clades at any time point (P >. 05). However, in competition assays, with 6 of the 7 pairs, clade B strains outcompeted clade A strains in their ability to persist in the GIT; this difference was significant in some pairs by day 2 and in all pairs by day 14 (P <. 0008-.0283). This observation may explain the predominance of clade B in the community and why antibiotic-resistant hospital-associated E. faecium are often replaced by clade B strains once patients leave the hospital.

Original languageEnglish (US)
Pages (from-to)1914-1922
Number of pages9
JournalJournal of Infectious Diseases
Issue number12
StatePublished - Jun 15 2016


  • Clades
  • Colonization
  • Enterococcus faecium
  • Fitness
  • GIT

ASJC Scopus subject areas

  • Immunology and Allergy
  • Infectious Diseases


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