**4. Enterococcus bacteriophages**

*E. faecalis* is one of the most frequently isolated species from nosocomial infections, endocarditis, bacteremia, urinary tract infections, meningitis, systemic infections. It has also been reported in periodontitis, which is a biofilm-mediated disease, tooth root infections, which are an example of endodontic biofilms, and also on implants. *E. faecalis* bacteriophages isolated belong to myoviridae and siphoviridae and are tailed phages. The bacteriophages isolated against *E. faecalis* strain of oral origin include phage IME-EF1 when administered intraperitoneally in a murine sepsis model protected the mice from lethal challenge around 60 to 80% mice surviving [17]. Another phage φEF 24C protected the BALB/C mouse model from the lethal challenge of *E. faecalis* [18]. Another phage EFDG1 tested on *E. faecalis* biofilms of post-treated root canal infections using an *ex vivo* two-chamber bacterial leakage model of human teeth showed dead bacteria in phage-treated teeth as compared to dentinal tubules of the control group [19]. The genetics of

three phages ϕEF11, EFDG1, and EFLK1 has been studied by genome sequencing [20]. Full-genome sequencing of the EFDG1 genome revealed that it did not contain harmful genes and also efficiently prevented *E. faecalis* infection after root canal treatment. The authors concluded that phage therapy using these phages might be efficacious to prevent *E. faecalis* infection after root canal treatment. *E. faecalis* has also been recovered from periodontal pockets in 1–51.8% of chronic periodontitis patients [21]. In our recent study, a novel *E. faecalis* bacteriophage was isolated from sewage and was found effective in reducing biofilms formed by drug-resistant clinical isolates of *E. faecalis* from chronic periodontitis patients [22]. Passage of phage ϕ EF11 through *E. faecalis* strains JH2–2 harboring a defective prophage produced a new strain with more antimicrobial efficacy [23]. The use of enterococci bacteriophages can probably control colonization of teeth surfaces by reducing the biofilm in chronic periodontitis. The application of bacteriophages as a strategy to conventional antibiotic treatment particularly in the case of biofilm and multidrugresistant strains is promising.
