Mucosal biofilm detection in chronic otitis media: a study of middle ear biopsies from Greenlandic patients

The objectives of this study were to examine middle ear biopsies from Greenlandic patients with chronic otitis media (COM) for the presence of mucosal biofilms and the bacteria within the biofilms. Thirty-five middle ear biopsies were obtained from 32 Greenlandic COM patients admitted to ear surgery. All biopsies were examined by means of peptide nucleic acid-fluorescent in situ hybridization (PNA-FISH), and if possible culture and polymerase chain reaction (PCR) of the 16s rDNA and sequencing. Light microscopy and confocal laser scanning microscopy were used. Skin biopsies from 23 of the patients served as controls. PNA-FISH showed morphological signs of biofilms in 15 out of 35 (43 %) middle ear biopsies. In the control skin biopsies, there were signs of biofilms in eight out of 23 biopsies (30 %), probably representing skin flora. PCR and 16s sequencing detected bacteria in seven out of 20 (35 %) usable middle ear biopsies, and in two out of ten (20 %) usable control samples. There was no association between biofilm findings and PCR and 16s sequencing. Staphylococci were the most common bacteria in bacterial culture. We found evidence of bacterial biofilms in 43 % of middle ear biopsies from patients COM. The findings may indicate that biofilms are a part of the pathogenesis in recurrent episodes of ear discharge in COM, but further investigations are necessary.