title: Transmission of diverse oral bacteria to murine placenta: evidence for the oral microbiome as a potential source of intrauterine infection.
abstract: Microbial infection of the intrauterine environment is a major cause of preterm birth. The current paradigm indicates that intrauterine infections predominantly originate from the vaginal tract, with the organisms ascending into the sterile uterus. With the improvements in technology, an increasing number of bacterial species have been identified in intrauterine infections that do not belong to the vaginal microflora. We have demonstrated previously that intrauterine infections can originate from the oral cavity following hematogenous transmission. In this study, we begin to systemically examine what proportion of the oral microbiome can translocate to the placenta. Pooled saliva and pooled subgingival plaque samples were injected into pregnant mice through tail veins to mimic bacteremia, which occurs frequently during periodontal infections. The microbial species colonizing the murine placenta were detected using 16S rRNA gene-based PCR and clone analysis. A diverse group of bacterial species were identified, many of which have been associated with adverse pregnancy outcomes in humans although their sources of infection were not determined. Interestingly, the majority of these species were oral commensal organisms. This may be due to a dose effect but may also indicate a unique role of commensal species in intrauterine infection. In addition, a number of species were selectively "enriched" during the translocation, with a higher prevalence in the placenta than in the pooled saliva or subgingival plaque samples. These observations indicate that the placental translocation was species specific. This study provides the first insight into the diversity of oral bacteria associated with intrauterine infection.
authors.affiliation: Department of Periodontics, School of Dental Medicine, Case Western Reserve University, Cleveland, Ohio 44106-4905, USA.
authors.forename: Yann
authors.initials: Y
authors.lastname: Fardini
authors.forename: Peter
authors.initials: P
authors.lastname: Chung
authors.forename: Rochelle
authors.initials: R
authors.lastname: Dumm
authors.forename: Nishiant
authors.initials: N
authors.lastname: Joshi
authors.forename: Yiping W
authors.initials: YW
authors.lastname: Han
mesh_terms: D000818:Animals; D001419:Bacteria / Q000145:classification / Q000235:genetics / Q000302:isolation & purification / Q000472:pathogenicity*; D001424:Bacterial Infections / Q000382:microbiology*; D044822:Biodiversity; D003773:Dental Plaque / Q000382:microbiology; D005260:Female; D006801:Humans; D008297:Male; D051379:Mice; D009055:Mouth / Q000382:microbiology*; D010920:Placenta / Q000382:microbiology*; D011247:Pregnancy; D012336:RNA, Ribosomal, 16S / Q000235:genetics; D012463:Saliva / Q000382:microbiology; D017422:Sequence Analysis, DNA
chemical_list: D012336:RNA, Ribosomal, 16S