Electronic Thesis and Dissertation Repository


Master of Science


Microbiology and Immunology


Dr. Gregor Reid


The oral cavity contains many different surfaces all colonized by prokaryotes, of which over 700 have been identified. While almost all people have some degree of plaque formation, the more concerning diseases of caries, candidiasis and periodontal disease afflict many patients and represent a major public health concern. As these are all diseases which have a component attributable to parts of the microbiota, efforts to manipulate the microbes has until recently involved use of antimicrobial agents. However, due to side effects, resistance and failure to restore homeostasis, this approach is limited. As an alternative, the administration of beneficial microbes (probiotics) has been considered. In this thesis, probiotic Streptococcus salivarius K12 and M18 and their by-products were shown to interfere with adhesion and coaggregation of pathogenic bacteria and yeast, and lower inflammatory factors. A human trial of healthy subjects showed the probiotics to be safe and not induce inflammation or disrupt the indigenous microbiota.

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Bacteriology Commons