title: Gastrointestinal Tract Colonization Dynamics by Different Enterococcus faecium Clades.
abstract: 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.
authors.affiliation: Department of Internal Medicine, Division of Infectious Diseases Center for the Study of Emerging and Re-emerging Pathogens Department of Microbiology and Molecular Genetics, University of Texas Graduate School of Biomedical Sciences at Houston, University of Texas Health Science Center at Houston.
authors.forename: Maria Camila
authors.initials: MC
authors.lastname: Montealegre
authors.affiliation: Department of Internal Medicine, Division of Infectious Diseases Center for the Study of Emerging and Re-emerging Pathogens.
authors.forename: Kavindra V
authors.initials: KV
authors.lastname: Singh
authors.affiliation: Department of Internal Medicine, Division of Infectious Diseases Center for the Study of Emerging and Re-emerging Pathogens Department of Microbiology and Molecular Genetics, University of Texas Graduate School of Biomedical Sciences at Houston, University of Texas Health Science Center at Houston.
authors.forename: Barbara E
authors.initials: BE
authors.lastname: Murray
mesh_terms: D000818:Animals; D000900:Anti-Bacterial Agents / Q000627:therapeutic use; D001422:Bacterial Adhesion; D004195:Disease Models, Animal; D004352:Drug Resistance, Microbial; D016984:Enterococcus faecium / Q000187:drug effects / Q000254:growth & development*; D005260:Female; D041981:Gastrointestinal Tract / Q000382:microbiology*; D016908:Gram-Positive Bacterial Infections / Q000382:microbiology*; D006801:Humans; D051379:Mice; D008813:Mice, Inbred ICR; D008826:Microbial Sensitivity Tests; D064307:Microbiota
chemical_list: D000900:Anti-Bacterial Agents
keywords: Enterococcus faecium; GIT; clades; colonization; fitness