External Auditory Canal Microbiome of Hearing aid users
The objective was to investigate the microbiota of hearing aid users external auditory canal (EAC) culture-independently and to compare it with EAC microbiota of control a group with no hearing aid use. Samples were collected with DNA-free swabs from the EACs of 50 hearing aid users (long-term use) and 80 working-age volunteers with asymptomatic EACs. Microbial communities in the samples were examined with amplicon sequencing of the 16S rRNA gene.  Twenty-four samples were excluded from the analyses, resulting with 48 hearing aid users, 59 controls for final analysis. Reasons for excluding samples were low sequence count, recent use of antimicrobials and/or corticosteroids, recent cold, or missing health status. The most common bacteria in the data were Staphylococcus auricularis, Alloiococcus otitis, Cutibacterium acnes, Corynebacterium otitidis and Staphylococcus unclassified sp. The hearing aid group differed from control group in bacterial diversity (beta div., p = 0.011) and hearing aid users showed lower species richness compared to the control group (alpha div., p < 0.01). Corynebacterium tuberculostearicum was more frequent in the hearing aid group and overall, the changes seemed to affect more commensal bacteria than increase pathogenic isolates.