A Transducing Bacteriophage InfectingStaphylococcus epidermidisContributes to the Expansion of a Novel Siphovirus Genus and Implies Genus is Inappropriate for Phage Therapy

The effort to discover novel phages infectingStaphylococcus epidermidiscontributes to both the development of phage therapy and the expansion of genome-based phage phylogeny. Here, we report the genome of anS. epidermidis–infecting phage SEP1 and compare its genome with five other sequenced phages with high sequence identity. These phages represent a novel siphovirus genus, which was recently reported in the literature. The published member of this group was favorably evaluated as a phage therapeutic agent, but SEP1 is capable of transducing antibiotic resistance. Members of this genus may be maintained within their host as extrachromosomal plasmid prophages, through stable lysogeny or pseudolysogeny. Therefore, we conclude that SEP1 may be temperate and members of this novel genus are not suitable for phage therapy.