The effect of ingestion of milk supplemented with salivaricin A-producing Streptococcus salivarius on the bacteriocin-like inhibitory activity of streptococcal populations on the tongue


  • Present address: Karen P. Dierksen, Department of Microbiology, Oregon State University, Corvallis, OR, USA.

  • Present address: Philip A. Wescombe, Chris J. Moore, BLIS Technologies Ltd, Centre for Innovation, Dunedin, New Zealand.

  • Editor: Julian Marchesi

Correspondence: John R. Tagg, Department of Microbiology and Immunology, University of Otago, PO Box 56, Dunedin, New Zealand. Tel.: +643 479 7714; fax: +643 479 8540; e-mail:


The colonization efficacies of salivaricin A (SalA)-producing Streptococcus salivarius strains 20P3 and 5 were compared when given in milk to 219 children, using either 2-day or 9-day dosing regimens. Colonization levels overall were superior for strain 5, and the 9-day dosing schedule resulted in higher levels of both initial colonization and strain persistence. The indigenous streptococcal tongue populations of 20 (10.9%) of the 189 children in the 2-day trial showed markedly increased SalA-like inhibitory activity following use of the S. salivarius-supplemented milk. All 20 of these children were found to have had relatively small (<5% of total S. salivarius) indigenous tongue populations of SalA-producing S. salivarius, and the relative proportions and/or inhibitory activity of these SalA producers on the childrens' tongues increased following ingestion of the S. salivarius-supplemented milk. Because SalA is known to be strongly inhibitory to Streptococcus pyogenes, an important implication of this study is that the consumption of SalA-producing probiotic S. salivarius could potentially help to effect a sustained increase in SalA-mediated protection against S. pyogenes infection.