The ENT microbiota

The ENT microbiota is an extremely diverse microbiota which is assumed to include at least 700 different species.

In the mouth, it is primarily found on the tongue, mucous  membranes, gums, and teeth, as well as in the saliva. Predominant phyla are Actinobacteria, Bacteroidetes, Firmicutes, Proteobacteria, and Synergistetes,¹ and primary genera are Streptococcus, Veillonella, Granulicatella, Granulicatella, Actinomyces, Corynebacterium, etc.²

In the nasal cavity, Actinobacteria and Firmicutes are predominant, with the occasional presence of Proteobacteria: Corynebacteriaceae and Propionibacteriaceae are the dominant families.³

In the ear, it was long believed that the area was exempt from any microbiota (because it was sterile), but since then a relatively diverse population of bacteria has been observed in the middle ear, with a predominance of Pseudomonadaceae.⁴ Recent studies have also shown evidence of the presence of Alloiococcus otitis,^5,6 Corynebacterium otitidis,^5,6 and Turicella otitidis.⁶ Although these bacteria are found in middle ear infections, their role in healthy individuals has yet to be elucidated, but it seems as though the ear canal might be a reservoir of infection for the middle ear.⁷

Dysbiosis and ENT diseases

An imbalance in the oral microbiota is at the root of diseases like cavities, gingivitis, and periodontitis, which are possible to prevent by fighting against the biofilm concentrating these pathogenic bacteria.2 Nasal microbiota is being investigated to understand its possible involvement in sinusitis, while more studies are needed to fully identify the role of the bacteria present in the ear.

Sources
1 – Wade WG. Detection and culture of novel oral bacteria. Chap. 2 de Oral microbial ecology – current research and new perspectives. Caister Academic Press, Norfolk (2013) http://www.caister.com/oral-ecology
2 – Zarco et al. The oral microbiome in health and disease and the potential impact on personalized dental medicine. Oral Diseases 2012 ; 18 : 109-120. https://www.ncbi.nlm.nih.gov/pubmed/21902769
3 – Bassis C et al. The nasal cavity microbiota of healthy adults. Microbiome 2014. 2 :27. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4138944/
4 – Liu CM et al. The otologic microbiome. Arch Otolaryngol Head Neck Surg 2011. 137(7) : 664-668. https://www.ncbi.nlm.nih.gov/pubmed/21768410
5 – Franck DN et al. Culture-independent molecular analysis of microbial constituents of the healthy human outer ear. J Clin Microbiol. 2003 Jan;41(1):295-303. https://www.ncbi.nlm.nih.gov/pubmed/12517864
6 – Stroman DW et al. Microbiology of normal external auditory canal. Laryngoscope. 2001 Nov ; 111(11 Pt 1) : 2054-9. https://www.ncbi.nlm.nih.gov/pubmed/11801996
7 - Chan CL et al. Identification of the Bacterial Reservoirs for the Middle Ear Using Phylogenic Analysis. JAMA Otolaryngol Head Neck Surg. 2017 Feb 1;143(2):155-161. https://www.ncbi.nlm.nih.gov/pubmed/27812691