Similarities have been observed between sinus and lower respiratory tract microbial community structures in patients with cystic fibrosis (CF), according to the results of a recently published longitudinal study in the journal Microbiology Spectrum.

The researchers sought to explore if changes to sinus microbial community diversity and specific taxa recognized to cause CF-related pulmonary disease are linked to increased respiratory disease and inflammation. The goal of the analysis was to assess how microbial composition and the inflammatory environment of the sinuses are linked to upper and lower airway disease in adults with CF chronic rhinosinusitis (CRS).

It is well known that CRS is a common, underreported, inadequately investigated upper respiratory tract disorder in individuals with CF. It has been suggested recently that the treatment of upper airway disease in patients with CF may lead to improvements in lower airway disease—that is, the treatment of upper respiratory tract symptoms can improve lower respiratory tract symptoms and vice versa.

Thirty-three adults with CF and symptomatic CRS who had undergone previous functional endoscopic sinus surgery were enrolled in the present study. During quarterly clinic visits, as well as unscheduled visits for exacerbation of clinical symptoms, 1 or more endoscopically guided specimens for 16S amplicon sequencing was obtained from 27 of the 33 participants. Additional samples included sinus secretions that were obtained to analyze inflammatory cytokines, bacterial cultures, and microscopy.

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On average, 5 longitudinal microbiota samples were obtained during study visits from 18 of 27 participants, and cross-sectional samples were obtained from 9 of 27 participants. The researchers were able to identify key drivers of microbial community composition and evaluate the relationships between diversity and taxa with disease outcomes and inflammation.

Results of the study showed that sinus community diversity was low and its composition was not fixed. Over time, many of the participants exhibited alternating dominance between Pseudomonas aeruginosa and staphylococci. Although these 2 taxa appeared to dominate, communities were highly personalized, with their composition shifting during the worsening of sinus disease symptoms. In fact, exacerbations were associated with communities that were dominated by Staphylococcus spp.

Decreased microbial community diversity was associated with worse sinus disease and with the inflammatory status of the sinuses, including increased interleukin-1β. Increased interleukin-1β itself was associated with worse sinus endoscopic appearance as well; other cytokines were associated with microbial community dynamics.

According to the authors, “A better understanding of CF sinus microbiology could provide a much-needed alternative site for monitoring respiratory infection status by important CF pathogens.”


Armbruster CR, Li K, Kiedrowski MR, et al. Low diversity and instability of the sinus microbiota over time in adults with cystic fibrosis. Microbiol Spectr. Published online September 12, 2022. doi:10.1128/spectrum.01251-22