Abstract
Background Parkinson’s disease (PD) compromises oral hygiene and oral health, potentially increasing oral bacterial input to the gut. Whether PD is associated with reproducible faecal enrichment of oral disease–linked taxa remains unclear.Objective To determine whether oral disease–linked taxa are enriched in the faecal microbiota of individuals with PD.Methods We conducted a pooled re-analysis of 23 faecal 16S rRNA datasets, comprising 3,594 PD and control samples. eHOMD was used to resolve oral-associated taxa, including caries/endodontic- and periodontitis-linked taxa. SILVA-based profiles were used to assess community diversity and ordination patterns. Differential-abundance analyses accounted for variation between studies.Results PD samples showed heterogeneous but reproducible enrichment of oral disease–linked taxa, with a prominent caries/endodontic-associated component. The cariogenic-enriched subgroup showed reduced evenness and increased representation of oral taxa including Streptococcus mutans. Beta-diversity analyses showed substantial PD-control overlap and an oralization-related compositional gradient rather than a discrete PD-specific cluster.Conclusions This pooled re-analysis identifies a gut oralization-associated signal in a subset of individuals with PD. Faecal enrichment of oral-associated taxa may represent one component of gut microbiome heterogeneity and may indirectly reflect variation in oral ecosystem status, supporting oral health assessment in future PD microbiome studies.