Metagenomics Analysis of Bacterial Population of Tympanosclerotic Plaques and Cholesteatomas

Abstract

Objective. Chronic otitis media can cause cholesteatomas or tympanosclerosis; however, the pathophysiology of such conditions is not completely known. The aim was to identify a bacterial genome that might be present in tympanosclerotic plaques and cholesteatomas using sequence analysis of the gene responsible for the transcription of 16 ribosomal RNA (rRNA). Study Design. Metagenomics analysis of the samples. Setting. Samples were collected and evaluated at tertiary care centers. Subjects and Methods. Sixty-five tympanosclerotic plaques and 37 cholesteatomas were evaluated. The polymerase chain reaction (PCR) was performed using primers designed for the amplification of the gene responsible for the transcription of bacterial 16 rRNA. The PCR-positive samples were sequenced via Sanger method, and 46 selected samples were analyzed with next-generation sequencing (NGS). Results. Sanger sequencing revealed the presence of bacterial genomes in a total of 18 of the 102 samples tested. Sequencing of these genomes indicated the presence of Alloiococcus otitis, Staphylococcus aureus, Achromobacter xylosoxidans, Escherichia coli, Staphylococcus sciuri, Staphylococcus caprae, Parvimonas spp., and Bacillus sp. in the tested samples. The NGS showed 1 or more different bacterial genomes in 44 (95.7%) of the 46 samples tested. Predominately, genome of Clostridiales (27 samples), Staphylococcaceae (24 samples), Peptoniphilaceae (12 samples), and Turicella otitidis (9 samples) were identified. Conclusion. The middle ear is inhabited by a diverse microbial community than that previously known. With the use of molecular biology, it has become easier to identify the bacterial genomes and improve our understanding of the role of middle ear microbiota in the pathogenesis of chronic inflammatory ear diseases.