Oral seeding and niche-adaptation of middle ear biofilms in health

Joo-Young Lee; Kristin M Jacob; Kazem Kashefi; Gemma Reguera

doi:10.1016/j.bioflm.2020.100041

Oral seeding and niche-adaptation of middle ear biofilms in health

Biofilm. 2021 Jan 6:3:100041. doi: 10.1016/j.bioflm.2020.100041. eCollection 2021 Dec.

Authors

Joo-Young Lee¹, Kristin M Jacob¹, Kazem Kashefi¹, Gemma Reguera¹

Affiliation

¹ Department of Microbiology and Molecular Genetics, Michigan State University, MI, USA.

Abstract

The entrenched dogma of a sterile middle ear mucosa in health is incongruent with its periodic aeration and seeding with saliva aerosols. To test this, we sequenced 16S rRNA-V4 amplicons from otic secretions collected at the nasopharyngeal orifice of the tympanic tube and, as controls, oropharyngeal and buccal samples. The otic samples harbored a rich diversity of oral keystone genera and similar functional traits but were enriched in anaerobic genera in the Bacteroidetes (Prevotella and Alloprevotella), Fusobacteria (Fusobacterium and Leptotrichia) and Firmicutes (Veillonella) phyla. Facultative anaerobes in the Streptococcus genus were also abundant in the otic and oral samples but corresponded to distinct, and sometimes novel, cultivars, consistent with the ecological diversification of the oral migrants once in the middle ear microenvironment. Neutral community models also predicted a large contribution of oral dispersal to the otic communities and the positive selection of taxa better adapted to growth and reproduction under limited aeration. These results challenge the traditional view of a sterile middle ear in health and highlight hitherto unknown roles for oral dispersal and episodic ventilation in seeding and diversifying otic biofilms.

Keywords: Divers; ET, Eustachian tube; Eustachian tube; Middle ear; OTUs, Operational taxonomic units; Oral dispersal; Otic infections; Otic microbiome; PCR, Polymerase chain reaction; PCoA, Principle coordinates analysis; rRNA, Ribosomal RNA.