Dysbiosis and Links of the Middle Ear, Nasal, and Oral Microbiota in Chronic Otitis Media with Effusion

Chronic otitis media with effusion (COME) is a common condition that can lead to hearing loss without acute inflammation. However, its underlying pathogenesis remains poorly understood, particularly with regard to microbial contributions. In this study, we characterized and compared the microbiota of the middle ear, nasal cavity, and oral cavity in 100 patients with COME and 77 controls using 16S rRNA gene sequencing. Alpha diversity, assessed by the Pielou index, was significantly reduced in the middle ear microbiota of COME patients compared with controls, and microbial compositions differed markedly across all sampled sites. Notably, <i>Aeromonas</i>, <i>Serratia</i>, and <i>Lactococcus</i> were enriched in both middle ear and nasal samples from COME patients. Among these, <i>Aeromonas</i> achieved the highest predictive value for COME in otic samples, whereas <i>Lactococcus</i> showed the strongest performance in nasal samples, with strong inter-site correlations. Functional analysis revealed the enrichment of pathways related to biofilm formation and depletion of antibiotic biosynthesis in COME-associated microbiota. These findings highlight the presence of microbial dysbiosis, particularly the interplay between nasal and middle ear microbiota, as a potential contributor to the COME pathogenesis, and suggest novel microbial targets for diagnosis and therapeutic intervention.