Biomarkers of Cigarette Smoking and Association with Vaginal Microbiota

Background:  Self-report of smoking has been identified in observational studies as a risk factor for bacterial vaginosis (BV). It is hypothesized that smoking leads to an accumulation of vaginal amines and that the anti-estrogenic effect of smoking predisposes a woman to BV. Trace amounts of benzo[a]pyrene diol epoxide (BPDE) are found in the vaginal secretions of women who smoke and BPDE significantly increases bacteriophage induction in lactobacilli. These results suggest that smoking may reduce the protective vaginal lactobacilli by promoting phage induction.

Objectives: We compared vaginal microbiota between smokers and non-smokers in a cross-sectional study using biomarkers of smoking.

Methods: Twenty smokers and 20 non-smokers self-collected mid-vaginal swabs. Vaginal smears were assessed using the Nugent Gram stain scoring method (0-3 categorized to normal, 4-6 as intermediate, and 7-10 as a high Nugent score indicative of BV). Smoking status was evaluated using both the semi-quantitative NicAlert® cotinine test and carbon monoxide exhalation.

Results: There were statistically significant tests of trend for increasing cotinine concentration and carbon monoxide exhalation with increasing Nugent score (p-value= 0.004 and p-value=0.005, respectively).  89% of women with high Nugent score compared to 29% of women with low Nugent score were classified to the highest nicotine concentration (>1000 ng/ml), p-value=0.025.  Similarly, 44% of women with high Nugent compared to 11% with low Nugent had a high carbon monoxide exhalation (>11ppm), p-value=0.012.

Conclusions:  When assessed by objective biomarkers, smoking is strongly associated with high Nugent score in a dose-response manner.

Implications for Programs, Policy, and Research: Disruptions of the vaginal microbiota and diagnosis of BV have been associated with a marked increased risk to the acquisition of HIV and STIs. Additional research is needed to examine if smoking cessation affects the vaginal microbiota. Work is ongoing to compare the vaginal microbiome between smokers and non-smokers using cultivation-independent tools.