Specific Lactobacillus/Mutans Streptococcus co-aggregation.

Selective interaction of mutans streptococci with benign bacteria could present an opportunity for their removal from the mouth without disruption of other oral flora. This study was conducted to find probiotic lactobacilli that could specifically co-aggregate in vitro with mutans streptococci, but not with other plaque commensals. A search of 624 lactobacilli among a large culture library revealed 6 strains, all classifiable as L. paracasei or L. rhamnosus, which met this criterion. Such novel, specific co-aggregation, however, was not a general characteristic of these species or the genus Lactobacillus. The co-aggregation by these specific lactobacilli was characterized as heat treatment (autoclaving)- and protease-resistant, lectin-independent, not inactivated by sugar substitutes, operational over a wide pH range, unaffected by whole saliva, but calcium-dependent. It is thus seen to present a potential strategy for in vivo alteration of plaque biofilm and caries.

Caries inhibition by and safety of Lactobacillus paracasei DSMZ16671.

Lactobacillus paracasei DSMZ16671, even if heat-killed, sensitively co-aggregates mutans streptococci specifically. Mutans streptococci are strongly implicated in caries induction in humans and rodents. We hypothesized: (1) that S. mutans recoveries from rats' teeth in vivo will decrease, with an associated decrease in caries, if these lactobacilli are fed to rats in an established caries model; and (2) that toxicological assays of these lactobacilli will show them to be benign. Four groups of specific-pathogen-free rats were formed: S. mutans 10449S-inoculated/16671-supplemented diet; un-inoculated/16671-supplemented diet; S. mutans 10449S-inoculated/placebo diet; and un-inoculated/placebo diet. Standard tests of toxicity and mutagenicity of heat-killed DSMZ16671 were performed. S. mutans recoveries were significantly reduced both in mid-experiment and at termination, as were caries lesion scores for the rats inoculated by S. mutans and fed the DSMZ16671 supplement, by comparison with controls. Neither toxicity nor mutagenicity of DSMZ16671 was detected. Use of heat-killed DSMZ16671 is efficacious in rats and appears safe.