The effect of corticosteroids on sinus microbiota in chronic rhinosinusitis patients with nasal polyposis

Abstract

Background: Chronic rhinosinusitis with nasal polyposis (CRSwNP) is a multifactorial disease with no known single cause, but it is thought that bacteria play a role in the disease process. The short-term response of bacterial communities to corticosteroid therapy has been found to be unpredictable. As a result, this pilot study aims to assess the long-term effect of corticosteroid therapy on sinus microbiota in chronic rhinosinusitis patients with nasal polyposis (CRSwNP). Methods: A longitudinal prospective case-control study was done on patients with CRSwNP and on healthy subjects. Patients with CRSwNP were randomly allocated to a maximal medical therapy (corticosteroids and antibiotics) treatment group or a corticosteroid-only treatment group. Data was collected at 3 time points (before treatment, 1 and 3 months after treatment): A guarded sinus swab was collected from the middle meatus; the SNOT-22 questionnaire was used to assess clinical symptoms. Specimens were cultured and Matrix-assisted laser desorption ionization–time of flight (MALDI-TOF) mass spectrometry (MS) was used as a bacterial detection method. The raw data produced was analyzed to characterize the sample and to assess the response to each medical treatment. Results: Data from 29 patients with CRSwNP (16 maximal medical therapy; 13 corticosteroids only) was compared to 15 healthy subjects. Patients reported significant symptoms improvement initially (1- month), but not on the long-term (3-months). This result was found as a response to both treatment groups, whether or not antibiotics was used. There was no significant difference in the sinus microbiota prevalence between CRSwNP patients and normal subjects. After three months from treatment, Corynebacterium genera tended to increase in the maximal medical therapy group, while Staphylococcus and gram-negative genera (Pseudomonas) tended to increase after corticosteroid treatment. Smoking, aspirin sensitivity and previous endoscopic sinus surgery were found to be co-factors significantly associated with the response to systemic corticosteroid therapy. Conclusion: In this pilot study both treatment options were effective on the short-term, but not on the long-term with no clear sinus microbiota response linked. As a result, this study agrees with previous reports that discourage the use of systemic antibiotics without evidence of active infection.