Vaginal microbiome dysbiosis and a rectal reservoir of uropathogens characterize postmenopausal women with recurrent urinary tract infections: a cross-sectional study.

INTRODUCTION

Recurrent urinary tract infections (rUTIs) in postmenopausal (PM) women pose a significant clinical challenge, complicated by rising antibiotic resistance among uropathogens. The vaginal microbiota in this population remains underexplored. We aim to characterize vaginal flora of PM women with and without a history of rUTIs, and to evaluate relationships to demographic variables, clinical characteristics, and rectal pathogen colonization.

METHODS

We conducted a cross-sectional study of 62 PM women (n = 31 rUTI, (n = 31 control). Vaginal swabs were analyzed using 16S rRNA and a next-generation sequencing tool designed to identify UTI pathogens and antibiotic resistance (AMR) markers. Rectal swabs were cultured to identify uropathogens and their phenotypic resistance. These were integrated with subject demographic and historical clinical data.

RESULTS

Compared to controls, rUTI vaginal microbiota exhibited a marked depletion in Lactobacillus crispatus and L. iners, species commonly associated with vaginal health, alongside an enrichment of L. gasseri and L. jensenii. The rUTI cohort also had a greater burden of AMR markers (p = 0.0003). Notably, Gram-negative uropathogens in the rUTI group frequently carried multidrug resistance genes, at rates nearly three times higher than controls. The rUTI cohort was further characterized by enrichment of Gram-negative uropathogens in the vagina. These alterations were more pronounced with increasing years in menopause.

DISCUSSION: The rectum emerged as a key reservoir, with notable concordance of organisms across rectal and urogenital sites. Our findings indicate that rUTIs in postmenopausal women are associated with a dysbiotic vaginal microbiome that is closely linked to a rectal reservoir of multidrug-resistant uropathogens.