The subgingival microbiome of clinically healthy current and never smokersOriginal paper
Karen Pendergrass is a microbiome researcher specializing in microbiome-targeted interventions (MBTIs). She systematically analyzes scientific literature to identify microbial patterns, develop hypotheses, and validate interventions. As the founder of the Microbiome Signatures Database, she bridges microbiome research with clinical practice. In 2012, based on her own investigative research, she became the first documented case of FMT for Celiac Disease, four years before the first published case study.
Read MoreWhat was studied?
This study examined whether cigarette smoking shapes the subgingival (below the gumline) bacterial community during states of clinical periodontal health, as a possible mechanism by which smoking raises the risk of periodontitis. Subgingival plaque was profiled by 16S pyrotag sequencing, combining the V1-V3 and V7-V9 regions of the 16S rRNA gene into a composite data set analyzed with the QIIME pipeline against the Greengenes database.
Who was studied?
The sample comprised 200 systemically and periodontally healthy adults aged 21 to 40 years, recruited as current smokers and never-smokers at The Ohio State University (USA) and Newcastle University (UK). The two groups were frequency-matched for age, gender, race/ethnicity, education, and socioeconomic status, and sequencing yielded about 1.58 million denoised, chimera-depleted sequences classified into 572 species-level operational taxonomic units (s-OTUs), with 155 (plus or minus 27) s-OTUs per person.
What were the most important findings?
Subgingival profiles differed between smokers and never-smokers at all taxonomic levels, with distinct clustering of communities by smoking status on principal coordinate analysis (P less than 0.001, ANOSIM), an effect that superseded ethnicity. Smokers showed a significantly higher Shannon diversity index (4.85 versus 4.35, P=0.01) with lower between-subject variance (P=0.0002), along with higher abundances of anaerobes and lower abundances of aerobes (P=0.02); 67 of 128 genera and 172 s-OTUs differed significantly, with the smoker community enriched for periodontal and systemic pathogens and depleted of health-compatible commensals.
What are the greatest implications of this study?
The authors conclude that smoking is associated with a pathogen-rich, commensal-poor, anaerobic subgingival microbiome that resembles a disease-associated community even in clinically healthy mouths, potentially priming the oral environment for a future ecological shift toward periodontitis. Because the design is observational and cross-sectional, these results indicate association rather than causation.