Biofilms in chronic suppurative otitis media and cholesteatoma: scanning electron microscopy findings

Biofilms play a role in the pathogenesis of a variety of otorhinolaryngologic diseases, including otitis media and cholesteatoma. Despite this, relatively few studies have undertaken to demonstrate the presence of biofilms tissues from patients with chronic otitis media or infected cholesteatoma.Our objective is to detect evidence of biofilms human chronic ear infections with scanning electron microscopy (SEM). We hypothesized that bacterial biofilms are present in patients with chronic otitis media.We performed prospective collection of tissue collected during middle ear surgery from 16 patients undergoing middle ear or mastoid surgery with chronic ear infections.A total of 31 middle and mastoid tissue samples were harvested at the time of surgery and processed with critical point drying for SEM analysis. Samples were then searched for evidence of biofilms.Bacterial-shaped objects were identified that displayed both surface binding and the presence of a glycocalyx in 4 patients, findings consistent with bacterial biofilms. Most of these (3 of 4) were in patients with infected cholesteatoma, and biofims were identified in 60% of cholesteatoma cases (3 of 5). On the other hand, only 1 of 7 cases with chronic suppurative otitis media had evidence of biofilms.SEM supports the hypothesis that bacterial biofilms are common in chronic infections associated with cholesteatoma and are present in some cases of chronic suppurative otitis media without cholesteatoma.