Microbiome of the Healthy External Auditory Canal

<jats:sec><jats:title>Objective:</jats:title><jats:p>To investigate the microbiota of the healthy external auditory canal (EAC) culture-independently and to evaluate the usefulness of the swabbing method in collecting EAC microbiota samples.</jats:p></jats:sec><jats:sec><jats:title>Study Design:</jats:title><jats:p>Cohort study.</jats:p></jats:sec><jats:sec><jats:title>Patients:</jats:title><jats:p>Fifty healthy asymptomatic working-age volunteers.</jats:p></jats:sec><jats:sec><jats:title>Intervention:</jats:title><jats:p>Samples were harvested with DNA-free swabs from the volunteers’ EACs.</jats:p></jats:sec><jats:sec><jats:title>Main Outcome Measures:</jats:title><jats:p>Amplicon sequencing of the 16S rRNA gene was used to characterize the microbial communities in the samples.</jats:p></jats:sec><jats:sec><jats:title>Results:</jats:title><jats:p>The swabbing method is feasible for EAC microbiota sample collection. The analyzed 41 samples came from 27 female and 14 male subjects; 4 samples were excluded due to recent antimicrobial treatment and 5 because of low sequence count or suspected contaminant microbes. The four most frequent amplicon sequence variants in the microbiota data were<jats:italic toggle="yes">Staphylococcus auricularis, Propionibacterium acnes, Alloiococcus otitis,</jats:italic>and<jats:italic toggle="yes">Turicella otitidis</jats:italic>. Typically, the dominant amplicon sequence variant in a sample was one of the most frequent bacteria, but there were also subjects where the dominant species was not among the most frequent ones. The genus<jats:italic toggle="yes">Alloiococcus</jats:italic>was least common in females who reported cleaning their ears. Subjects with a high relative abundance of<jats:italic toggle="yes">Alloiococcus</jats:italic>typically had a low abundance of<jats:italic toggle="yes">Staphylococcus,</jats:italic>which may be a sign of the two being competing members of the microbial community.</jats:p></jats:sec><jats:sec><jats:title>Conclusions:</jats:title><jats:p>The most common bacteria in the microbiome of the healthy EAC were<jats:italic toggle="yes">Staphylococcus auricularis, Propionibacterium acnes, Alloiococcus otitis,</jats:italic>and<jats:italic toggle="yes">Turicella otitidis</jats:italic>. The EAC microbiota seems more diverse and individualized than previously thought. Also, ear cleaning habits seem to alter the EAC microbiome.</jats:p></jats:sec>