title: Raising the Alarmone: Within-Host Evolution of Antibiotic-TolerantEnterococcus faecium.
abstract: Enterococci are ancient commensal bacteria that recently emerged as leading causes of antibiotic-resistant, hospital-acquired infection. Vancomycin-resistant enterococci (VRE) epitomize why drug-resistant enterococcal infections are a problem: VRE readily colonize the antibiotic-perturbed gastrointestinal (GI) tract where they amplify to large numbers, and from there, they infect other body sites, including the bloodstream, urinary tract, and surgical wounds. VRE are resistant to many antimicrobials and host defenses, which facilitates establishment at the site of infection and confounds therapeutic clearance. Having evolved to colonize the GI tract, VRE are comparatively ill adapted to the human bloodstream. A recent study by Honsa and colleagues (E. S. Honsa et al., mBio 8:e02124-16, 2017, https://doi.org/10.1128/mBio.02124-16) found that a strain of vancomycin-resistantEnterococcus faeciumevolved antibiotic tolerance within the bloodstream of an immunocompromised host by activating the stringent response through mutation ofrelAPrecisely how VRE colonize and infect and the selective pressures that led to the outgrowth ofrelAmutants are the subjects of ongoing research.
authors.affiliation: Department of Ophthalmology, Harvard Medical School, Massachusetts Eye and Ear Infirmary, Boston, Massachusetts, USA vantyne@fas.harvard.edu michael_gilmore@meei.harvard.edu.|Department of Microbiology and Immunobiology, Harvard Medical School, Boston, Massachusetts, USA.
authors.forename: Daria
authors.initials: D
authors.lastname: Van Tyne
authors.affiliation: Department of Ophthalmology, Harvard Medical School, Massachusetts Eye and Ear Infirmary, Boston, Massachusetts, USA vantyne@fas.harvard.edu michael_gilmore@meei.harvard.edu.|Department of Microbiology and Immunobiology, Harvard Medical School, Boston, Massachusetts, USA.
authors.forename: Michael S
authors.initials: MS
authors.lastname: Gilmore
mesh_terms: D000900:Anti-Bacterial Agents; D016983:Enterococcus / Q000187:drug effects; D016984:Enterococcus faecium / Q000187:drug effects*; D041981:Gastrointestinal Tract / Q000187:drug effects; D016908:Gram-Positive Bacterial Infections; D006801:Humans; D014640:Vancomycin; D020713:Vancomycin Resistance / Q000187:drug effects
chemical_list: D000900:Anti-Bacterial Agents; D014640:Vancomycin