Cigarette smoking and oral microbiota in low-income and African-American populations

Background Cigarette smoking is a common risk factor for diseases and cancers. Oral microbiota is also associated with diseases and cancers. However, little is known about the impact of cigarette smoking on the oral microbiota, especially among ethnic minority populations. Methods We investigated cigarette smoking in relationship with the oral microbiota in a large population of predominately low-income and African-American participants. Mouth rinse samples were collected from 1616 participants within the Southern Community Cohort Study, including 592 current-smokers, 477 former-smokers and 547 never-smokers. Oral microbiota was profiled by 16S ribosomal RNA gene deep sequencing. Results Current-smokers showed a different overall microbial composition from former-smokers (p=6.62×10 -7) and never-smokers (p=6.00×10 -8). The two probiotic genera, Bifidobacterium and Lactobacillus, were enriched among current-smokers when compared with never-smokers, with Bonferroni-corrected p values (P Bonferroni) of 1.28×10 -4 and 5.89×10 -7, respectively. The phylum Actinobacteria was also enriched in current-smokers when compared with never-smokers, with a median relative abundance of 12.35% versus 9.36%, respectively, and with a P Bonferroni =9.11×10 -11. In contrast, the phylum Proteobacteria was depleted in current smokers (P Bonferroni =5.57×10 -13), with the relative abundance being almost three times that of never-smokers (7.22%) when compared with that of current-smokers (2.47%). Multiple taxa within these two phyla showed differences in abundance/prevalence between current-smokers and never-smokers at P Bonferroni <0.05. The differences in the overall microbial composition and abundance/prevalence of most taxa were observed among both African-Americans and European-Americans. Meanwhile, such differences were not observed between former-smokers and never-smokers. Conclusion Smoking has strong impacts on oral microbial community, which was recovered after smoking cessation.