E-cigarette users and smokers had significantly higher amounts of Staphylococcus aureus in their respiratory microbiome than nonsmokers, and microbial diversity differed by sex, according to a new analysis. Researchers in a new study also found that Lactobacillus iners, usually seen as a protective species, was more prevalent in smokers than in nonsmokers, whereas less prevalent in e-cigarette users than in nonsmokers.
The respiratory microbiome is thought to help protect the lower respiratory tract from pathogens, but the specific effects of e-cigarettes on the respiratory or nasal microbiome have not been well studied, wrote Elise Hickman, PhD, of the Center for Environmental Medicine, Asthma and Lung Biology at The University of North Carolina at Chapel Hill, and colleagues.
“Identifying how e-cigarette use modifies the nasal microbiome is another step in understanding how vaping affects lung health,” said lead investigator Ilona Jaspers, PhD, in an interview.
In a study published in Nicotine & Tobacco Research, the investigators used 16S rRNA gene sequencing to examine the respiratory microbiomes of 57 healthy adults aged 18-50 years: 20 nonsmokers, 28 e-cigarette users, and 19 smokers. The researchers collected serum cotinine measurements as an indicator of nicotine exposure, and participants completed questionnaires as to their smoking habits.
Smokers reported an average of 12.68 cigarettes per day. The 13 e-cigarette users who reported puffs per day averaged 53.90 puffs per day, and the 16 who reported mL of liquid per day and e-liquid nicotine concentration averaged 3.60 mL of e-liquid and 19.43 mg/mL of nicotine in e-liquids.
Overall, the researchers found an increase in S aureus in smokers and e-cigarette users compared with nonsmokers. By contrast, L iners was more abundant in smokers than in nonsmokers but less abundant in e-cigarette users than in nonsmokers.
Notably, among e-cigarette users, the microbial beta diversity was significantly different between male and female participants, although this was not the case in cigarette smokers.
For example, Propionibacterium acnes was decreased in smokers and e-cigarette users compared with nonsmokers. However, men demonstrated an increase in Haemophilus parainfluenzae and P acnes and a decrease in S aureus compared with women.
The researchers also stratified smokers and e-cigarette users into groups based on cotinine (a nicotine metabolite) to examine the impact of nicotine on changes in the nasal microbiota. Among smokers, microbial diversity was significantly decreased in those with cotinine levels> 151 ng/mL vs those with cotinine levels ≤ 151 ng/mL. However, the opposite was true for the e-cigarette users (P
Source : Medscape