# Bacteriome of the Middle Ear in Children and Young Adults With Cholesteatoma and Retraction Pocket: A Pilot Study

## TL;DR

This pilot study compares the bacterial communities in the middle ears of children with cholesteatoma or retraction pockets to healthy controls, finding significant differences.

## Contribution

The study is the first to compare middle ear bacteriomes in cholesteatoma, retraction pockets, and healthy ears using 16S rDNA sequencing.

## Key findings

- Middle ear samples from COM patients showed low bacterial diversity, often dominated by one or two bacterial genera.
- A significantly higher proportion of cholesteatoma and RP patients had detectable bacterial genera compared to controls.
- Bacteriomes in cholesteatoma and RP were similar, suggesting RP may be a precholesteatoma stage.

## Abstract

Chronic otitis media (COM) is a common middle ear disease in children and young adults. Dysfunction of the Eustachian tube and bacterial infection are the main causes. This pilot study aimed to describe and compare bacteriomes of the middle ear in children and young adults with serious forms of COM, such as cholesteatoma and retraction pocket (RP) of the tympanic membrane, with bacteriomes in healthy middle ears.

Observational study.

Clinical practice in a tertiary center. From January 1, 2021 to August 31, 2022. Patients aged 0 to 20 years.

In this case‐control study, middle ears were swabbed during surgery on children with cholesteatoma (N = 23) or RP (N = 26) and on children indicated for cochlear implant (N = 15, controls). Genomic DNA extraction was followed by creation of a 16S ribosomal DNA gene library and sequencing on a MiSeq instrument. Samples with relative abundance of at least one bacterial genus >20% were considered positive for the specific genus.

Bacterial diversity was generally low in the middle ear samples from patients with COM, with DNA content from 1 or 2 bacteria usually dominating in the sample. A significant difference in positivity for one or more bacterial genera was observed between patients with cholesteatoma or RP (38.8%) versus patients indicated for cochlear implants (6.7%).

While middle ear bacteriomes in cases of cholesteatoma and RP differed from those of controls, findings in the 2 pathological conditions were similar. These results support the statement that the RP could be a precholesteatoma stage.