title: Large-scale screening of a targeted Enterococcus faecalis mutant library identifies envelope fitness factors.
abstract: Spread of antibiotic resistance among bacteria responsible for nosocomial and community-acquired infections urges for novel therapeutic or prophylactic targets and for innovative pathogen-specific antibacterial compounds. Major challenges are posed by opportunistic pathogens belonging to the low GC% gram-positive bacteria. Among those, Enterococcus faecalis is a leading cause of hospital-acquired infections associated with life-threatening issues and increased hospital costs. To better understand the molecular properties of enterococci that may be required for virulence, and that may explain the emergence of these bacteria in nosocomial infections, we performed the first large-scale functional analysis of E. faecalis V583, the first vancomycin-resistant isolate from a human bloodstream infection. E. faecalis V583 is within the high-risk clonal complex 2 group, which comprises mostly isolates derived from hospital infections worldwide. We conducted broad-range screenings of candidate genes likely involved in host adaptation (e.g., colonization and/or virulence). For this purpose, a library was constructed of targeted insertion mutations in 177 genes encoding putative surface or stress-response factors. Individual mutants were subsequently tested for their i) resistance to oxidative stress, ii) antibiotic resistance, iii) resistance to opsonophagocytosis, iv) adherence to the human colon carcinoma Caco-2 epithelial cells and v) virulence in a surrogate insect model. Our results identified a number of factors that are involved in the interaction between enterococci and their host environments. Their predicted functions highlight the importance of cell envelope glycopolymers in E. faecalis host adaptation. This study provides a valuable genetic database for understanding the steps leading E. faecalis to opportunistic virulence.
authors.affiliation: INRA, UMR1319 Micalis, Jouy-en-Josas, France.
authors.forename: Lionel
authors.initials: L
authors.lastname: Rigottier-Gois
authors.forename: Adriana
authors.initials: A
authors.lastname: Alberti
authors.forename: Armel
authors.initials: A
authors.lastname: Houel
authors.forename: Jean-François
authors.initials: JF
authors.lastname: Taly
authors.forename: Philippe
authors.initials: P
authors.lastname: Palcy
authors.forename: Janet
authors.initials: J
authors.lastname: Manson
authors.forename: Daniela
authors.initials: D
authors.lastname: Pinto
authors.forename: Renata C
authors.initials: RC
authors.lastname: Matos
authors.forename: Laura
authors.initials: L
authors.lastname: Carrilero
authors.forename: Natalia
authors.initials: N
authors.lastname: Montero
authors.forename: Muhammad
authors.initials: M
authors.lastname: Tariq
authors.forename: Harma
authors.initials: H
authors.lastname: Karsens
authors.forename: Christian
authors.initials: C
authors.lastname: Repp
authors.forename: Andrea
authors.initials: A
authors.lastname: Kropec
authors.forename: Aurélie
authors.initials: A
authors.lastname: Budin-Verneuil
authors.forename: Abdellah
authors.initials: A
authors.lastname: Benachour
authors.forename: Nicolas
authors.initials: N
authors.lastname: Sauvageot
authors.forename: Alain
authors.initials: A
authors.lastname: Bizzini
authors.forename: Michael S
authors.initials: MS
authors.lastname: Gilmore
authors.forename: Philippe
authors.initials: P
authors.lastname: Bessières
authors.forename: Jan
authors.initials: J
authors.lastname: Kok
authors.forename: Johannes
authors.initials: J
authors.lastname: Huebner
authors.forename: Fatima
authors.initials: F
authors.lastname: Lopes
authors.forename: Bruno
authors.initials: B
authors.lastname: Gonzalez-Zorn
authors.forename: Axel
authors.initials: A
authors.lastname: Hartke
authors.forename: Pascale
authors.initials: P
authors.lastname: Serror
mesh_terms: D000818:Animals; D000900:Anti-Bacterial Agents / Q000494:pharmacology; D001422:Bacterial Adhesion / Q000187:drug effects; D018938:Caco-2 Cells; D002462:Cell Membrane / Q000187:drug effects / Q000378:metabolism*; D024881:Drug Resistance, Bacterial / Q000187:drug effects / Q000235:genetics; D013293:Enterococcus faecalis / Q000187:drug effects / Q000235:genetics* / Q000254:growth & development / Q000472:pathogenicity; D004847:Epithelial Cells / Q000187:drug effects / Q000378:metabolism / Q000382:microbiology; D015723:Gene Library; D018390:Gene Targeting; D005798:Genes, Bacterial / Q000235:genetics; D005820:Genetic Testing; D016908:Gram-Positive Bacterial Infections / Q000382:microbiology; D006801:Humans; D023421:Models, Animal; D008954:Models, Biological; D009036:Moths / Q000187:drug effects / Q000382:microbiology; D009154:Mutation / Q000235:genetics*; D009895:Opsonin Proteins / Q000378:metabolism; D010587:Phagocytosis / Q000187:drug effects; D010641:Phenotype; D010957:Plasmids / Q000235:genetics; D013312:Stress, Physiological / Q000187:drug effects / Q000235:genetics; D014774:Virulence / Q000187:drug effects / Q000235:genetics; D037521:Virulence Factors / Q000235:genetics / Q000378:metabolism*
chemical_list: D000900:Anti-Bacterial Agents; D009895:Opsonin Proteins; D037521:Virulence Factors