The effect of antibiotics on the microbiome in acute exacerbations of chronic rhinosinusitis.

Background: Current treatment of acute exacerbations of chronic rhinosinusitis (CRS) is driven by identification of predominant bacteria using culture-based methods and determination of antibiotic sensitivities. The objective of this study was to evaluate the response of the sinonasal microbiome to antibiotic therapy in the setting of an acute exacerbation of CRS.
Methods: Aspirate and swab samples for culture and DNA analysis were collected bilaterally from 8 CRS patients presenting with acute exacerbations. Patients were started on a 2-week course of a culture-directed antibiotic after sensitivities were determined. Repeat samples were taken immediately on the completion of treatment. DNA was extracted from each sample, amplified using bacterial 16S primers and sequenced. Bacterial abundance was determined by quantitative polymerase chain reaction (qPCR). Diversity metrics of the microbiota between pretreatment and posttreatment samples were calculated.
Results: There was significantly more bacterial DNA present in the pretreatment group than in the posttreatment group. An increase in α-diversity was found in the posttreatment group relative to the pretreatment group (p < 0.05 in each comparison) with swab sampling, but not by aspirate sampling. The predominant organism identified by 16S sequencing correlated with the culture-identified bacteria genus in each patient.
Conclusion: Significant differences exist in the diversity of bacteria populations during acute exacerbations of CRS and after antimicrobial treatment. After therapy, the increase in diversity is accompanied by a decrease in the total of abundance of the bacterial population.
(© 2015 ARS-AAOA, LLC.)