title: Effect of a genetically engineered bacteriophage on Enterococcus faecalis biofilms.
abstract: OBJECTIVE
  Enterococcus faecalis is a Gram-positive, facultative anaerobic bacterium that is associated with failed endodontic cases and nosocomial infections. E. faecalis can form biofilms, penetrate dentinal tubules and survive in root canals with scarce nutritional supplies. These properties can make E. faecalis resistant to conventional endodontic disinfection therapy. Furthermore, treatment may be complicated by the fact that many E. faecalis strains are resistant to antibiotics. A potential alternative to antibiotic therapy is phage therapy. ϕEf11 is a temperate phage that infects strains of E. faecalis. It was previously sequenced and genetically engineered to modify its properties in order to render it useful as a therapeutic agent in phage therapy. In the current study, we have further genetically modified the phage to create phage ϕEf11/ϕFL1C(Δ36)PnisA. The aim of this study was to evaluate the efficacy of bacteriophage ϕEf11/ϕFL1C(Δ36)PnisA, to disrupt biofilms of two Enterococcus faecalis strains: JH2-2 (vancomycin-sensitive) and V583 (vancomycin-resistant).
  
  
  METHODS
  24h static biofilms of E. faecalis strains JH2-2(pMSP3535 nisR/K) and V583 (pMSP3535nisR/K), formed on cover slips, were inoculated with bacteriophage ϕEf11/ϕFL1C(Δ36)PnisA. After 24 and 48h incubation, the bacterial biomass was imaged by confocal microscopy and viable cells were quantified by colony forming unit measurement.
  
  
  RESULTS
  The results showed a 10-100-fold decrease in viable cells (CFU/biofilm) after phage treatment, which was consistent with comparisons of treated and untreated biofilm images visualized as max projections of the Z-series.
  
  
  CONCLUSIONS
  The biomass of both vancomycin-sensitive and vancomycin-resistant E. faecalis biofilms is markedly reduced following infection by bacteriophage ϕEf11/ϕFL1C(Δ36)PnisA.
authors.affiliation: Department of Endodontology, School of Dentistry, State University of Rio de Janeiro, Rio de Janeiro, RJ 20551-030, Brazil. Electronic address: justinemonnerat@yahoo.com.br.
authors.forename: Justine Monnerat
authors.initials: JM
authors.lastname: Tinoco
authors.affiliation: Department of Microbiology & Immunology, School of Medicine, Temple University, Philadelphia, PA 19140, USA.
authors.forename: Bettina
authors.initials: B
authors.lastname: Buttaro
authors.affiliation: Department of Endodontology, School of Dentistry, Temple University, Philadelphia, PA 19140, USA.
authors.forename: Hongming
authors.initials: H
authors.lastname: Zhang
authors.affiliation: Department of Endodontology, School of Dentistry, Temple University, Philadelphia, PA 19140, USA.
authors.forename: Nadia
authors.initials: N
authors.lastname: Liss
authors.affiliation: Department of Endodontology, School of Dentistry, State University of Rio de Janeiro, Rio de Janeiro, RJ 20551-030, Brazil.
authors.forename: Luciana
authors.initials: L
authors.lastname: Sassone
authors.affiliation: Department of Endodontology, School of Dentistry, Temple University, Philadelphia, PA 19140, USA.
authors.forename: Roy
authors.initials: R
authors.lastname: Stevens
mesh_terms: D001435:Bacteriophages; D018441:Biofilms; D018533:Biomass; D013293:Enterococcus faecalis / Q000187:drug effects / Q000502:physiology*; D005818:Genetic Engineering / Q000379:methods; D016908:Gram-Positive Bacterial Infections / Q000382:microbiology / Q000517:prevention & control*; D018613:Microscopy, Confocal; D016133:Polymerase Chain Reaction; D020713:Vancomycin Resistance
keywords: Antimicrobial; Bacteriophage therapy; Biofilm; Enterococcus faecalis; Public health; Resistance