Otitis media with effusion is not a sterile inflammatory process: scanning electron microscope evidence

Purpose: We aimed to demonstrate whether chronic otitis media with effusion (OME) is a sterile condition or biofilms-related disease through direct visualization of middle ear mucosa by Scanning electron microscopy (SEM) and culture of the effusion.

Methods: This case-control study included 60 children in two groups; the case group included 50 patients undergoing ventilation tube insertion (VTI) for Chronic OME (COME), and the control group included ten patients undergoing cochlear implantation (CI) surgery presenting normal middle ear mucosa. Biopsies from both groups' middle ear mucosa were evaluated for biofilm formation using scanning electron microscopy (SEM). Middle ear effusion (MEE) samples from COME patients were cultured on blood agar to detect and identify any bacterial growth. The adenoid size was evaluated and correlated to the biofilm formation in COME patients.

Results: There was a significant difference between case and control groups regarding biofilm formation (p-value < 0.001*). Biofilm was evident in 84% of the COME patients (cases group) and absent in the control group. Only 12 COME patients (24%) had positive MEE culture, however, 76.2% of patients with biofilm had a negative culture. Streptococcus pneumonia was the most common otopathogen found either alone or combined with other otopathogens. There was a significant negative correlation between adenoid size and biofilm grade among the studied patients.

Conclusion: The visual identification of middle ear biofilms indicated their role in chronic OME. Middle ear biofilms need to be expected in children with OME, especially those who do not need adenoid surgery.