Relationship between oral bacteria and Pulmonary Abscess/Pyothorax. Streptococcus constellatus subsp. constellatus

Some pathogens in pyothorax or pulmonary abscess is thought to be derived from the oral cavity; however it has not been proven genetically. In this study, we examined genetic homology using a next-generation sequencer. In National Hospital Organization of Himeji Medical Center, subsequent patients with pulmonary abscess or pyothorax were recruited. Oral bacterial flora was obtained by wiping the oral cavity. Pus was collected by percutaneous needle aspiration and cultured. The isolated strain was identified based on 16S rRNA. We limited genetic homology study to the species which have genome information disclosed on the internet to design the isolated strain-specific primer. We also limited the homology study to the strains which contained **>= copies/ml of oral sample enough for PCR. The whole genome of the isolated strain was sequenced using an Illumina Miseq sequencer. We designed 5 sets of isolated strain-specific primers compared with the genome information of the same species on the internet. Total DNA of oral bacterial flora was amplified by PCR using these primers, and the sequence of the amplicons was analyzed for the homology. Between Aug 1, 2013, and Mar 27, 2015, 42 patients were recruited. **4 patients with pulmonary abscess and 4 with pyothorax were eligible for genetic homology test. Streptococcus anginosus group (n=6), Parvimonas micra (n=1), and Fusobacterium nucleatum (n=1) were isolated from pus. In all patients, all amplified sequences in oral bacterial flora completely matched the genome sequence of the isolated strain, but did not perfectly match the genome for the same species in database disclosed on the internet. To our knowledge, this is the first report proving that bacteria isolated from pulmonary abscess or pyothorax are identical to oral bacteria at the strain level based on genetic homology.