Staphylococcus aureus in nasal lavage and biopsy of patients with chronic rhinosinusitis

Abstract

Background: Staphylococcus aureus may play a relevant etiologic role in chronic rhinosinusitis (CRS) and may explain the T_H2 shift observed in CRS with nasal polyps (CRSNP⁺). Naturally occurring S. aureus small colony variants (SASCV) escape immune surveillance, antibiotic treatment and microbiologic routine diagnostic techniques. The frequency of S. aureus and SASCV in CRS patients and S. aureus-related effects on the local immune response should be prospectively investigated. Methods: Nasal lavages and mucosal biopsies of CRS patients were examined with bacterial culture suitable for detecting SASCV, real time PCR and fluorescence in situ hybridization. To assess the effects of S. aureus positivity, interleukin-5 (IL-5), interferon-γ, total immunoglobulin E (IgE), eotaxin, granulocyte-colony stimulating factor, and eosinophil cationic protein in nasal lavages were determined and gene transcription analysis of nasal biopsies from S. aureus positive and negative CRSNP⁺ patients was performed. Results: Thirty-one CRSNP⁺ patients, 13 CRS patients without polyps, and 21 control patients were evaluated. Staphylococcus aureus was detected by any method in 25 patients (39%). Staphylococcus aureus detection rates did not differ between the three disease groups (P = 0.3). Staphylococcus aureus small colony variants were not found. In nasal lavages, IL-5 and total IgE levels were higher in CRSNP⁺ patients than in CRSNP⁻ patients or controls (P < 0.05). Staphylococcus aureus positivity did not influence biomarker concentrations in nasal lavages. Genes for T_H2 cytokines were not differentially transcribed. Conclusions: We could not observe a higher prevalence of S. aureus in CRS patients with or without nasal polyps than in controls. We could not substantiate that S. aureus intensifies the T_H2 shift in CRSNP⁺ patients. Staphylococcus aureus small colony variants were not detected in any sample.