Suppression of Periodontal Pathogenic Bacteria in the Saliva of Humans by the Administration of Lactobacillus salivarius TI 2711

The ability of Lactobacillus salivarius TI 2711 (LS 1) to displace periodontopathic bacteria, like Porphyromonas gingivalis and Prevotella intermedia, was studied using humanvolunteers. LS 1 was one thousandfold more susceptible to lactic acid than Lactobacillus acidophilus, a representative acid-resistant Lactobacillus strain frequently found at the sites of caries, when these bacteria were exposed to 50 mM of lactic acid. In an in vitro system, LS 1 completely killed P. gingivalis within 24 hours when these bacteria were cultured together. In a clinical study, 57 subjects took tablets containing 2×107 CFU or more of LS 1 daily for 4 or 8 weeks. The number of black-pigmented anaerobic rods, which includes most periodontopathic bacteria, in the saliva decreased to one-twentieth of the initial value after 4 weeks, whereas the numbers of whole bacteria, Streptococcus mutans and lactobacilli did not change. While the saliva pH was widely distributed (ranging from 5. 4 to 8. 5) before LS 1 treatment, it converged to within a neutral range of around 7. 3 after treatment. Thus, the possibility that LS 1 accelerates caries formation by lowering the pH in the oral cavity was excluded. These findings suggest that LS 1 may be, potentially useful probiotic agent against periodontopathic bacteria. J Jpn Soc Periodontol, 45 : 105-112, 2003.