In vitro inhibitory effect of two commercial probiotics on chromogenic actinomycetes

Abstract

Purpose: Black extrinsic discoloration is a common clinical and aesthetic problem. This study aims to evaluate the potential in vitro antagonistic activity of two commercial probiotics, Streptococcus salivarius M18 and Lactobacillus reuteri ProDentis, against microorganisms associated with black stains.

Methods: Streptococcus salivarius M18 and Lactobacillus reuteri were tested against Aggregatibacter actinomycetemcomitans and Actinomyces naeslundiiusing their cell-free fermentative broth in a planktonic growth inhibition test.

Results: Both probiotic cell-free supernatants showed the ability to reduce the pathogenic bacteria growth in a dose-dependent way. Streptococcus salivarius M18 showed a stronger antimicrobial activity than Lactobacillus reuteri ProDentis against the two indicator strains used. A. naeslundi was less susceptible to the probiotic activity of both S. salivarius and L. reuteri compared to A. actinomycetemcomitans.

Conclusions: The obtained results demonstrate a potent antagonistic ability of probiotics to reduce the growth of microorganisms associated with black tooth stains. Therefore, these strains could be evaluated for a therapeutic use against dental pigmentations.

Keywords: Actinomyces naeslundii; Aggregatibacter actinomycetemcomitans; Black stain; Lactobacillus reuteri; Streptococcus salivarius M18.