The composition of the bacteria found in liver, spleen, oral cavity and fecal samples of mice subjected to an experimental periodontitis model

Periodontitis patients often develop bacteremia, but there has been little evidence showing that oral bacteria translocate into other organs. We found that bacterial colony formation occurs in a culture of liver and spleen cells of periodontitis-induced mice, and the bacterial species detected in the liver and spleen were found in the oral cavity as well, but not in fecal samples, indicating systemic dissemination of oral bacteria during the breakdown of the oral barrier. We performed this experiment to check if the bacteria found in liver and spleen originated from oral cavity or the gut during periodontitis. Bacterial DNA was extracted from the periodontitis-inducing ligature, fecal sample and tissue cultures with a NucleoSpin® Tissue Kit (Takara). The V4 region of 16S rRNA genes was PCR amplified (25 cycles, primer pair F515/R806), followed by barcoding (8 cycles) using a Nextera XT Index Kit v2 (Illumina) in triplicate. Barcoded amplicons were sequenced (150-bp paired-end sequencing) on an Illumina MiSeq (Illumina).