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. 2025 May 18;13(5):1154.
doi: 10.3390/microorganisms13051154.

Oral Microbiota Dysbiosis in Firefighters and the Potential Contributing Environmental and Lifestyle Factors Based on a Case-Control Study

Sukanta S Bhattacharya  1 , Brijesh Yadav  1 , Roman Jandarov  2 , William A Jetter  3   4 , Jagjit S Yadav  1
Affiliations

Oral Microbiota Dysbiosis in Firefighters and the Potential Contributing Environmental and Lifestyle Factors Based on a Case-Control Study

Sukanta S Bhattacharya et al. Microorganisms. .

Abstract

Epidemiological studies show firefighters have increased risks of cancer, diabetes, and cardiovascular disease. To explore links between occupational/environmental exposures and dysbiosis-associated health risks, this case-control study compared oral microbiota of age-matched firefighters (n = 13) and non-firefighters (n = 13) using next-generation sequencing. Firefighters exhibited significantly reduced overall microbial diversity (p ≤ 0.05) and compositional shifts. Firmicutes increased from 53.5% to 68.5%, and Bacteroidetes from 9.5% to 14.1%, while Proteobacteria decreased from 24.6% to 8.3%, and Fusobacteria from 3.3% to 1.1%. This resulted in a higher Firmicutes to Bacteroidetes ratio (5.63 vs. 4.89 in controls), indicating a pro-inflammatory oral microenvironment. At the family level, Streptococcaceae (45.1% to 60.3%) and Prevotellaceae (6.2% to 10.0%) increased, whereas Neisseriaceae (17.7% to 4.9%) and Fusobacteriaceae (2.1% to 0.8%) decreased. The genus Streptococcus dominated firefighters' microbiota, rising from 45.1% to 60.3%. Diversity indices confirmed reduced microbial evenness and richness in firefighters. Metadata analysis linked frequent fire exposures to perturbations in Comamonadaceae and Carnobacteriaceae (p ≤ 0.05). Barbecue consumption, a source of polycyclic aromatic hydrocarbons, correlated with elevated Spirochaetaceae and Peptostreptococcaceae. This first report on oral dysbiosis in firefighters reveals significant alterations in microbiota abundance, diversity, and evenness, implying potential health risks for this group.

Keywords: PAHs; cancer; dysbiosis; firefighters; occupational exposure; oral microbiome.

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Conflict of interest statement

The authors declare no conflict of interest.

Figures

Figure 1
Figure 1
Study workflow used to evaluate shift in oral microbiome in firefighters.
Figure 2
Figure 2
Oral dysbiosis in firefighter group as compared to the control group, depicted in terms of relative abundance (%) of major Phyla (A), Classes (B), Families (C), and Genera (D).
Figure 3
Figure 3
Oral microbiota alpha- and beta-diversity changes in firefighters group as compared to the control group, depicted in terms of the Shannon diversity index (A), Shannon evenness index (B), Bray-Curtis index (C), Simpson dominance index (D), and Chao1 index (E). * Depicts statistical significance (p ≤ 0.05).
See this image and copyright information in PMC

References

    1. Yadav B., Mohammed A.N., Graham B., Bhattacharya A., Yadav J.S. Chronic Heat Exposure Modulates Innate and Adaptive Immune Responses in Firefighters. Environments. 2024;11:131. doi: 10.3390/environments11060131. - DOI
    1. Stec A.A., Dickens K.E., Salden M., Hewitt F.E., Watts D.P., Houldsworth P.E., Martin F.L. Occupational Exposure to Polycyclic Aromatic Hydrocarbons and Elevated Cancer Incidence in Firefighters. Sci. Rep. 2018;8:2476. doi: 10.1038/s41598-018-20616-6. - DOI - PMC - PubMed
    1. Woodall C.A., Hammond A., Cleary D., Preston A., Muir P., Pascoe B., Sheppard S.K., Hay A.D. Oral and gut microbial biomarkers of susceptibility to respiratory tract infection in adults: A feasibility study. Heliyon. 2023;9:e18610. doi: 10.1016/j.heliyon.2023.e18610. - DOI - PMC - PubMed
    1. Gustavsson P., Jakobsson R., Johansson H., Lewin F., Norell S., Rutkvist L.E. Occupational exposures and squamous cell carcinoma of the oral cavity, pharynx, larynx, and oesophagus: A case-control study in Sweden. Occup. Environ. Med. 1998;55:393–400. doi: 10.1136/oem.55.6.393. - DOI - PMC - PubMed
    1. Chen K.M., Guttenplan J.B., Zhang S.M., Aliaga C., Cooper T.K., Sun Y.W., DelTondo J., Kosinska W., Sharma A.K., Jiang K., et al. Mechanisms of oral carcinogenesis induced by dibenzo[apyrene: An environmental pollutant and a tobacco smoke constituent. Int. J. Cancer. 2013;133:1300–1309. doi: 10.1002/ijc.28152. - DOI - PMC - PubMed