Bacteriophages have been found to have significant influence in various microbial environments. Little is known about the impact of bacteriopahges on the oral ecology. Bacteriophages specific for oral bacteria such as Actinobacillus actinomycetecomitans and Actinomyces viscosus were previously isolated from dental plaque. To the best of our knowledge this is the first report of the presence of phages in human saliva and of an oral Enterococcus faecalis bacteriophage.
Oral bacterial strains used in this study were: Streptococcus mutans ATCC 2735, Streptococcus sobrinus 6715, Streptococcus salivarius ATCC 11742, Actinomyces viscosus ATCC 43146 and E. faecalis DJ1 (an oral isolate). Salivary samples were taken from 31 volunteers mean age of 25. Our results show that after three to five days of inoculation with E. feacallis, uniform turbid lysis zones (2mm in diameter) were detected in saliva samples collected from 7 out of 31 individuals. Phage activity against the other tested bacterial species could not be detected. The E. feacalis phages were re-isolated from one individual tested 4 weeks and one year after initial sample collection.
Transmission electron microscopy revealed uniformed, spherical, enveloped, spiked, structures with a diameter of roughly 70nm. Phage tail was not detected.
. The presence of bacteriophages in human saliva and the observation of their prolong persistence (one year) in the saliva of one of the individuals tested, demonstrate an easy route of phage transfer and suggest that phages might play an active and an important role in the oral environment. The relative high incidence (22%) of E. faecalis phages found in human saliva screened in this study suggests that phages might exhibit control over the oral E. faecalis population and restrict its outbreaks to the relative isolated and protected location of the teeth’s root system. If this assumption is correct, phage therapy as a way to prevent endodontic inflammation cause by E. faecalis might be considered.