Characteristics of the esophageal microbiota in patients with Achalasia

Background: Achalasia（AC）is clinically characterized by chronic intraluminal food stasis and bacterial fermentation, which may contribute to esophageal dysbiosis. This study aims to characterize the esoph-ageal microbiome in AC patients, identify key biomarkers, and elucidate their correlations with clinical and electrophysiological parameters to advance our understanding of AC pathogenesis. Methods : In this single-center case-control study, we performed 16S rRNA sequencing on esophageal mucosal samples from achalasia patients and controls. We analyzed diversity, identified differential taxa (LEfSe), predicted functions (PICRUSt), and correlated microbiota with clinical measures. Biomarkers were determined via random forest and validated by qPCR. Results: Achalasia patients exhibited significant esophageal microbial dysbiosis characterized by struc-tural alterations in community composition without marked diversity changes. We observed pronounced enrichment of opportunistic Fusobacterium with concomitant depletion of beneficial Akkermansia and Ligilactobacillus. Pseudomonas and Ralstonia abundances correlated with symptom severity. Fusobac-terium enrichment was confirmed by qPCR validation. Functional prediction indicated upregulated ace-tyl-CoA biosynthesis in patients. Importantly, Fusobacterium levels showed positive correlations with key clinical parameters: lower/upper esophageal sphincter pressures and Eckardt dysphagia scores, sug-gesting its potential role in achalasia pathophysiology. Conclusions: Esophageal dysbiosis is associated with esophageal hypomotility in achalasia patients.