16s RNA-based metagenomics reveal previously unreported gut microbiota associated with reactive arthritis and undifferentiated peripheral spondyloarthritis.

This article focuses on the characterization of gut microbiota associated with reactive arthritis (ReA) and undifferentiated peripheral spondyloarthritis (UpSpA). Using metagenomic 16S rRNA sequencing of stool samples from 55 patients (20 with gut-associated ReA and 35 with UpSpA) and 36 healthy controls, the study found that ReA and UpSpA share similar gut microbial compositions, supporting their combined consideration in research. Compared with healthy controls, patients exhibited significantly higher gut microbial diversity and distinct differences in microbial taxa, including increased abundance of Proteobacteria and pathobionts such as Staphylococcus aureus, Escherichia coli, and Klebsiella pneumoniae. The findings suggest that both known and novel bacterial species may contribute to the pathogenesis of ReA/upSpA, highlighting the potential role of gut microbiota in these inflammatory arthritides.