Recolonization dynamics of the middle ear microbiota following MESNA-assisted dissection in pediatric...

Cholesteatomatous chronic otitis media (CCOM) remains a clinical challenge due to its high recurrence rates despite surgical intervention. Sodium 2-mercaptoethanesulphonate (MESNA) is used to assist dissection, yet its impact on the middle ear microbiome and ecological recovery remains poorly understood. The aim of this study is to characterize the microbiota of paediatric CCOM and evaluate the ecological shifts induced by MESNA-assisted surgery.

We analyzed 16S rRNA gene sequences (V3-V4) from middle ear tissue of paediatric patients with CCOM (CCOM Before MESNA, n = 13; CCOM After MESNA, n = 13) and healthy controls (n = 11). Bioinformatic processing was performed via QIIME2 and DADA2. We employed a Compositional Data Analysis (CoDA) framework, centering on Aitchison distances, ALDEx2 for differential abundance, and consensus co-occurrence networks (SparCC, SPIEC-EASI, and CLR-Pearson). Functional potential was inferred using PICRUSt2.

CCOM was associated with a marked reduction in microbial network connectivity, decreasing from 185 edges in healthy controls to only two total edges in the CCOM Before MESNA stage. Cutibacterium emerged as a candidate keystone pathobiont, exhibiting profound ecological isolation and predicted metabolic shifts toward lipid catabolism and biofilm formation in dysbiotic states. MESNA application disrupted the disease-associated community equilibrium, initiating secondary succession. However, post-treatment recovery was marked by taxonomic homogenization and the expansion of Pseudomonas in several patients.

Our findings identify network fragmentation and functional dysbiosis as the ecological signatures of pediatric CCOM. While MESNA disrupts the dysbiotic equilibrium, it does not fully restore a healthy stable climax community within the studied timeframe, as defined in ecological succession theory. These results support a paradigm shift from simple pathogen eradication toward ecological restoration as a strategy to prevent disease recurrence in CCOM patients.