The effect of cigarette smoking on the oral and nasal microbiota

Abstract

Background: The goal of the study was to investigate whether cigarette smoking alters oral and nasal microbial diversity, composition, and structure. Twenty-three current smokers and 20 never smokers were recruited. From each subject, nine samples including supra and subgingiva plaque scrapes, saliva, swabs from five soft oral tissue sites, and one nasal swab from both the anterior nares were collected. 16S rRNA V3-V4 region was sequenced for microbial profiles.

Results: We found that alpha diversity was lower in smokers than in nonsmokers in the buccal mucosa, but in other sample sites, microbial diversity and composition were not significantly different by smoking status. Microbial profiles differed significantly among eight oral sites.

Conclusions: This study investigates the effect of cigarette smoking on different sites of the oral cavity and shows a potential effect of cigarette smoking on the buccal mucosa microbiota. The marked heterogeneity of the oral microbial ecosystem that we found may contribute to the stability of the oral microbiota in most sites when facing environmental perturbations such as that caused by cigarette smoking.

Keywords: 16S rRNA and cigarette smoke; Microbiota; Nasal cavity; Oral cavity.

Fig. 1

a Sampling of nine samples from each subject following the protocols used by HMP. b Shannon’s index by smoking status and sample sites. The Shannon index did not significantly differ by smoking status in any sample sites. c Within- and between-group (smoker, nonsmoker) weighted UniFrac distance (beta diversity). Within- versus between-group differences were not statistically significant by permutational multivariate analysis of variance (adonis). In Figure b and c, the boxes are interquartile range (IQR); median values are the bands within the boxes; the lines outside the boxes are 1.5-times IQR; dots are outliers. d Mean and 95% interval of genus-relative abundance. Streptococcus was most abundant in all sites, but no genus was significantly different in relative abundance by smoking status according to the Wilcoxon rank-sum test with Bonferroni correction. Only the five most abundant genera are shown

Fig. 2

a Comparison of Shannon’s index (alpha diversity) across eight oral sites. The pairwise comparison by Wilcoxon signed-rank tests are shown in Additional file 2: Table S3. b Genus-level profiles and dendrogram showing similarity and difference among oral sites. The dendrogram at the top was based on hierarchical clustering using complete linkage of Bray-Curtis distance of the OTU table. Splits seen in at least 70% of 1000 bootstrap sampling are shown. Each vertical bar represents the profile averaged within each sample site. The average relative abundance (%) is shown in parenthesis after each genus. Only the most abundant genera are shown