Molecular Characterization of the Polymicrobial Flora in Chronic Rhinosinusitis

Introduction: Conventional cultures have implicated Staphylococcus aureus (SA) and coagulase-negative Staphylococcus (CNS) as principal pathogens in chronic rhinosinusitis (CRS). These results are questioned by recent studies in which molecular probes implicate Haemophilus influenzae instead.

Objectives: To identify all bacterial species present on sinonasal mucosa using molecular culture (bacterial tag-encoded FLX amplicon pyrosequencing [bTEFAP]) and to compare them with those identified with conventional methods.

Methods: A prospective study of 18 patients undergoing endoscopic sinus surgery for CRS and 9 control patients with pituitary adenomas was conducted. Per-operative mucosal biopsies were assessed with bTEFAP by sequencing the species-specific 16S ribosomal deoxyribonucleic acid (DNA) fragment for genetic identification of bacteria and then compared with simultaneous swab culture.

Results: Standard cultures showed mainly SA and CNS. Molecular cultures identified up to 20 organisms per sample. Surprisingly, anaerobic species predominated (Diaphorobacter and Peptoniphilus). SA was nevertheless detected in 50%.

Conclusion: Molecular cultures such as bTEFAP are sensitive tools for bacterial identification in CRS and suggest that anaerobe involvement may be more frequent than presumed.