Urobiome Signatures of Recurrent Urinary Tract Infections in Adolescent Pregnancy: A Longitudinal Study

Adolescent pregnancy is a significant public health concern, with maternal and fetal risks compounded by pregnancy-related anatomical, hormonal, and urinary changes that predispose to urinary tract infections (UTIs). Alterations in the urinary microbiome may further influence infection susceptibility, yet little is known about its role during adolescent pregnancy. This study analyzed the urinary microbiome of adolescent pregnant patients and its association with UTI and recurrent UTI (rUTI) across gestation. Healthy adolescents were enrolled in the first trimester and followed through subsequent trimesters, with urine samples collected at each visit for microbiological diagnosis. Patients were classified as healthy (34 samples), single UTI (22 samples), or rUTI (31 samples), and oxford-nanopore 16S rRNA sequencing was used to assess taxonomic composition, microbial diversity, and operational taxonomic units. Distinct trimester-specific patterns were observed, with Lactobacillus iners progressively increasing and L. kitasatonis emerging as a dominant taxon during adolescent pregnancy. Interestingly, rUTI cases showed persistent E. coli, reduced L. kitasatonis and L. ultunensis in the second trimester, and the appearance of Fannyhessea vaginae (Atopobium vaginae) in the third. These findings suggest a potential microbial signature of rUTI in adolescent pregnancy, underscoring the need for personalized preventive strategies and the establishment of microbiome-based clinical cutoffs.