The Use of Streptococcus salivarius to Target Periodontal Pathogens

Abstract

Periodontitis is a disease that is characterised by inflammation of the gums and subsequent loss of teeth which affects up to 57% of the world’s population. Key pathogens implicated in periodontitis include Porphyromonas gingivalis, Prevotella intermedia and Fusobacterium nucleatum. Each can invade and survive inside oral epithelial cells, allowing for recurrence of disease after treatment with antimicrobials. The oral commensal Streptococcus salivarius produces bacteriocin-like inhibitory substances (BLIS), which can interfere with the growth of bacteria of other species. Although haemolysin production is uncommon in S. salivarius, it may help them enter and survive intracellularly, similar to the way that listeriolysin O contributes to the invasion and intracellular survival of Listeria monocytogenes. It is proposed that a β-haemolytic S. salivarius producing BLIS activity against periodontal pathogens may have potential application to the management and prevention of periodontal disease. In this study, strong inhibitors of P. intermedia include the P-type 777 S. salivarius strains K12, Min5, Mia and CCUG11878. Furthermore, strain K12 and its variants were able to adhere strongly to HEp-2 cells. S. salivarius strains shown to produce haemolysins include Carl1, H3, Tove-R and 3638. Preliminary indications are that more than one type of haemolysin may be produced by S. salivarius, as indicated by haemolysin production by some strains being favoured on different types of blood agar media. This study is the first to report the potential use of S. salivarius to target intracellular periodontal pathogens. Increased understanding of the mechanisms of action of S. salivarius inhibitory agents against periodontal pathogens and its ability to inhibit intracellular infection by periodontal pathogens in a mammalian cell line may lead to the potential use of S. salivarius as a probiotic to improve overall oral health, particularly in those affected by or who are at risk of periodontitis.