Molecular characterization of the polymicrobial flora in chronic rhinosinusitis

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.

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.

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.

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%.

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