This study analyses which bacteria are present in the middle ear space and adjacent upper respiratory tract niches in healthy people and in patients suffering from chronic otitis media with effusion (OME; glue ear). The aim is to identify and isolate bacteria that are more common and more abundant in healthy people and to evaluate their potential to protect against bacteria commonly involved in OME and other upper respiratory tract infections.

To this end, samples will be collected from both groups (healthy vs OME) and analysed through sequencing of the bacterial 16S gene. In addition, samples obtained from healthy participants will be cultivated to isolate bacteria of interest.

Inclusion Criteria:

• Controls: undergo a surgery that gives access to the middle ear space (at least 30 participants; e.g. cochlear implant recipients) or the adenoids.
• OME patients: have fluid accumulation in the middle ear space for 3+ months and receive ventilation tubes. May also undergo adenoidectomy.

Exclusion Criteria:

• Acute upper respiratory tract infections (including acute otitis media)
• Chronic upper respiratory tract infections (except OME in patient group)
• URT malformations (e.g. as seen in people with Down Syndrome or cleft palate)
• Cystic fibrosis
• Autoimmune diseases or immunodeficiency
• Pregnancy
• Use of antibiotics or steroids 1 week before surgery

100 healthy participants vs 100 OME patients.