Characteristics of the esophageal microbiome in patients with achalasia and its changes before and after peroral endoscopic myotomy: A pilot study

Achalasia often presents with chronic food stasis and fermentation in the esophageal lumen, which may lead to alterations of the esophageal microbiome, with associated mucosal inflammation and dysplastic changes. The study aims to evaluate the characteristics of the esophageal microbiome in achalasia and changes of the esophageal microbiome before and after peroral endoscopic myotomy (POEM).This is a prospective case-control study. This study enrolled patients with achalasia and asymptomatic subjects as control group. Endoscopic brushing for esophageal microbiome collection was performed in all subjects, with additional follow-up endoscopy and brushing 3 months after POEM in achalasia patients. The composition of the esophageal microbiome was determined and compared between (1) achalasia patients and asymptomatic controls and (2) achalasia patients before and after POEM.Thirty-one achalasia patients (mean age 53.5 ± 16.2 years; male 45.2%) and 15 controls were analyzed. We observed a distinct esophageal microbial community structure in achalasia patients, with increased Firmicutes and decreased Proteobacteria when compared with the control group at the phylum level. The discriminating enriched genera in achalasia patients were Lactobacillus, followed by Megasphaera and Bacteroides, and the amount of Lactobacillus was associated with the severity of achalasia. Twenty patients were re-examined after POEM, and a high prevalence of erosive esophagitis (55%) was noted, alongside an increase in genus Neisseria and decrease in Lactobacillus and Bacteroides.The altered esophageal microenvironment in achalasia leads to dysbiosis with a high abundance of genus Lactobacillus. Increased Neisseria and decreased Lactobacillus were observed after POEM. The long-term effect of microbial changes warrants further study.