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The development of probiotics targeting non-intestinal body sites continues to generate interest amongst researchers, biotech companies and consumers alike. A key consideration for any bacterial strain to be developed into a probiotic is a robust assessment of its safety profile. Streptococcus salivarius strain M18 was originally isolated from a healthy adult and evaluated for its probiotic capabilities targeted to dental and oral health applications. This publication presents the safety characterisation of strain M18. Application of a diverse range of techniques showed that strain M18 can be specifically distinguished from other S. salivarius using a variety of molecular and phenotypic methodologies and that it lacks any relevant antibiotic resistance or virulence determinants. Direct comparison of the strain M18 safety profile with that of the prototype S. salivarius probiotic, S. salivarius strain K12, supports the proposition that strain M18 is indeed safe for probiotic application in humans.

Abstract: Streptococci commonly produce bacteriocin-like inhibitory substances (BLIS). Inhibitory molecules characterized to date have included members of bacteriocin classes I, II and III. Streptococcus salivarius, Streptococcus mutans and Streptococcus uberis strains frequently produce multiple bacteriocins of these various classes. Lantibiotics belonging to the streptococcin A-FF22 (SA-FF22) and salivaricin A (SalA) clusters are produced by several oral streptococcal species. Multi-bacteriocin-producing streptococci such as S. salivarius strain K12, which contain a variety of bacteriocin loci located on mega-plasmids, are now finding application as oral probiotics. [Copyright &y& Elsevier]

Aims: To determine whether dosing with bacteriocin-producing Streptococcus salivarius following an antimicrobial mouthwash effects a change in oral malodour parameters and in the composition of the oral microbiota of subjects with halitosis. Materials and Results: Twenty-three subjects with halitosis undertook a 3-day regimen of chlorhexidine (CHX) mouth rinsing, followed at intervals by the use of lozenges containing either S. salivarius K12 or placebo. Assessment of the subjects’ volatile sulphur compound (VSC) levels 1 week after treatment initiation showed that 85% of the K12-treated group and 30% of the placebo group had substantial (>100 ppb) reductions. The bacterial composition of the saliva was monitored by culture and PCR-denaturing gradient gel electrophoresis (PCR-DGGE). Changes in the PCR-DGGE profiles occurred in most subjects following K12 treatment. In vitro testing showed that S. salivarius K12 suppressed the growth of black-pigmented bacteria in saliva samples and also in various reference strains of bacteria implicated in halitosis. Conclusions: Administration of bacteriocin-producing S. salivarius after an oral antimicrobial mouthwash reduces oral VSC levels. Significance and Impact of the Study: The outcome of this preliminary study indicates that the replacement of bacteria implicated in halitosis by colonization with competitive bacteria such as S. salivarius K12 may provide an effective strategy to reduce the severity of halitosis. [ABSTRACT FROM AUTHOR]

Seven beta-hemolytic Streptococcus salivarius isolates produced bacteriocin-like inhibitory activity in deferred antagonism tests using a set of nine indicator bacteria (I1 -I9). Five of these S. salivarius strains (KWF, TOVE-R, K17, K21, and K26) were inhibitory to indicators I2, I5, I6, and I7. Mutated non-hemolytic derivatives showed concomitant loss of inhibitory activity against I2, I5, and I6, but retained activity against I7. Inhibitory activity against I2, I5, and I6 was restored in beta-hemolytic revertants of such mutants. Strain 3638 was inhibitory to all of the indicator organisms except I3, and this pattern of inhibitory activity was retained by non-hemolytic derivatives. It appeared that strain 3638 produced an additional broadly-active inhibitory agent, since a mutant (strain 3638A), which was apparently defective in the production of this inhibitor, retained both the beta- hemolytic and I2-, I5-, I6-, and I7-inhibitory activities. Non-hemolytic derivatives of strain 3638A were inhibitory only to I7. Strain 3638, therefore, appeared to produce at least three inhibitory agents: one active only on I7; another acting on I2, I5, and I6 (and associated with beta-hemolytic activity); and a third apparently active on all of the indicators other than I3. S. salivarius strain JH inhibited all nine indicator strains and possessed a beta-hemolytic character which differed from that of the other strains in being readily eliminated on treatment with the plasmid-curing agent novobiocin. Non-hemolytic derivatives of JH retained inhibitory activity against the complete set of indicators. The results of this study suggest that hemolysin production by some S. salivarius strains may be intimately associated with a distinctive type of bacteriocin-like activity. [ABSTRACT FROM AUTHOR]

A powder preparation of the oral probiotic Streptococcus salivarius K12 has been given to 19 young otitis media-prone children following a 3-day course of amoxicillin administered as a preliminary to ventilation tube placement. In two subjects, the use of strain K12 appeared to effect the expansion of an indigenous population of inhibitory S. salivarius. In other children, strain K12 colonisation extended beyond the oral cavity to also include the nasopharynx or adenoid tissue. The relatively low proportion (33%) of subjects that colonised was attributed to failure of the amoxicillin pre-treatment to sufficiently reduce the indigenous S. salivarius populations prior to dosing with strain K12 powder. [ABSTRACT FROM AUTHOR]