Periodontitis is an inflammatory disease that is characterized by progressive destruction of the periodontium and causes tooth loss in adults. Periodontitis is known to be associated with dysbiosis of the oral microflora, which is often linked to various diseases. However, the complexity of plaque microbial communities of periodontitis, antibiotic resistance, and enhanced virulence make this disease difficult to treat. In this study, using metagenomic shotgun sequencing, we investigated the etiology, antibiotic resistance genes (ARGs), and virulence genes (VirGs) of periodontitis. We revealed a significant shift in the composition of oral microbiota as well as several functional pathways that were represented significantly more abundantly in periodontitis patients than in controls. In addition, we observed several positively selected ARGs and VirGs with the Ka/Ks ratio > 1 by analyzing our data and a previous periodontitis dataset, indicating that ARGs and VirGs in oral microbiota may be subjected to positive selection. Moreover, 5 of 12 positively selected ARGs and VirGs in periodontitis patients were found in the genomes of respiratory tract pathogens. Of note, 91.8% of the background VirGs with at least one non-synonymous single-nucleotide polymorphism for natural selection were also from respiratory tract pathogens. These observations suggest a potential association between periodontitis and respiratory infection at the gene level. Our study enriches the knowledge of pathogens and functional pathways as well as the positive selection of antibiotic resistance and pathogen virulence in periodontitis patients, and provides evidence at the gene level for an association between periodontitis and respiratory infection.

牙周炎是一种炎症性疾病，其特征是牙周组织的进行性破坏，并导致成人牙齿脱落。众所周知，牙周炎与口腔微生物群落的生态失调有关，而口腔微生物群落通常与各种疾病有关。然而，牙周炎菌斑微生物群落的复杂性、抗生素耐药性和增强的毒力使该病难以治疗。在这项研究中，我们使用宏基因组鸟枪法测序，调查了病因、抗生素抗性基因(ARG) 和毒力基因(VirGs) 牙周炎。我们揭示了口腔微生物群组成的显着变化以及牙周炎患者比对照组更丰富的几种功能途径。此外，我们通过分析我们的数据和之前的牙周炎数据集，观察到几个 Ka/Ks 比率 > 1 的正选 ARGs 和 VirGs，表明口腔微生物群中的 ARGs 和 VirGs 可能受到正选择。此外，在呼吸道病原体的基因组中发现了牙周炎患者中 12 个阳性选择的 ARG 和 VirG 中的 5 个。值得注意的是，具有至少一种用于自然选择的非同义单核苷酸多态性的背景 VirGs 中有 91.8% 也来自呼吸道病原体。基因水平的呼吸道感染。我们的研究丰富了病原体和功能通路的知识，以及牙周炎患者抗生素耐药性和病原体毒力的阳性选择，并在基因水平上为牙周炎和呼吸道感染之间的关联提供了证据。