Medical therapy reduces microbiota diversity and evenness in surgically recalcitrant chronic rhinosinusitis

Abstract

Background: Chronic rhinosinusitis (CRS) is a highly prevalent and heterogeneous condition frequently treated with antibiotics and corticosteroid therapy. However, the effect of medical therapy on sinus microbiota remains unknown.

Methods: We enrolled CRS patients (n = 6) with patent maxillary antrostomies and active mucosal inflammation, who had not received antibiotics or corticosteroids in the previous 8 weeks. A pretreatment and posttreatment maxillary sinus swab was collected, from which DNA was extracted, pyrosequenced, and analyzed using a naïve Bayesian classifier and ecological analyses.

Results: Four patients showed significant improvement in endoscopic appearance. The shifts in microbiota in response to therapy were highly individualized. There was no single common microbiota profile among patients with similar clinical outcomes, but overall there was significant decrease in microbiota diversity (t(5) = 2.05, p = 0.10) and evenness (t(5) = 2.28, p = 0.07) after treatment.

Conclusion: Our findings strongly correlate with earlier studies that examined the impact of antibiotics on human microbiota. We observed that posttreatment, patients frequently became colonized by taxa that are less susceptible to the prescribed antibiotics. Our findings highlight the challenge in seeking generalizable diagnostic and therapeutic options in CRS, particularly regarding microbiological response and outcomes.

Keywords: 16S rRNA gene; Microbiology; Sinusitis, eosinophilic rhinitis; chronic rhinosinusitis; maximum medical therapy; microbiome; microbiota; nasal polyposis.

Figure 1

Effects of clinically indicated maximum medical therapy on the sinus microbiota. In this heatmap visualization, each column represents the change in sinus microbiota from an individual. Along each row, the change in the proportional abundance of a bacterial taxon (e.g., Pseudomonas) is shown and can be interpreted using the annotated color-coding key (right, color bar), which denotes each of the color that correlates with its respective proportional abundance change.

Figure 2

Maximum medical therapy is associated with decrease in sinus microbiota richness (Figure 2A), as well as microbiota diversity (Figure 2B, left) and evenness (Figure 2B, right). Figure 2A is the collector's curve, which represents the total number of unique bacterial taxon found in participants before (solid line) or after (dashed line) treatment as each participant is analyzed. This showed the total number of unique taxa decreased after treatment. In the two sets of plots in Figure 2B, each data point represents the evenness and Shannon Diversity value either before or after treatment in a single participant, and is labeled by the Participant study ID. At each time point, the mean value is annotated by a simple horizontal line.