Shared mechanisms of recurrent Escherichia coli urinary tract infections in humans and dogs: the role of vaginal colonization and microbiota dynamics

• Applicant: Dr. Sophie Aurich
• Subject Area: Veterinary Medical Science
• Term: since 2026
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 570422334

Urinary tract infections (UTIs) are the second most common reason for antibiotic prescriptions in both humans and dogs, with Escherichia (E.) coli as the predominant pathogen. Approximately 20 % of women and 5.7 % of dogs with UTI experience recurrence. This project investigates the role of vaginal colonization and microbiota interactions across vaginal, intestinal and urinary compartments in women and dogs with recurrent E. coli UTI, focusing on E. coli reservoir and shared mechanisms of recurrent UTI (rUTI) across host species. We hypothesize that vaginal colonization plays a key role in UTI development. Specifically, dominant or virulent E. coli strains, originating from the host’s intestinal tract, may colonize the vaginal microbiota, ascend to the urinary tract, and establish persistent or intermittent bacteriuria, ultimately leading to infection. To test this hypothesis, we will utilize established cohorts of female dogs from Denmark and German women to examine how changes in the composition of vaginal, urinary, and faecal microbiota contribute to E. coli dominance. This will involve a combination of culture methods, whole genome sequencing, shotgun metagenomics, and long-read sequencing of the flagellin gene and/or short-read sequencing of single-locus informative markers (SLIMs) as well as single nucleotide polymorphisms (SNPs). Our approach will identify dominant E. coli strains, their abundance in each sample, and their genetic and virulence traits. Functional assays will assess whether dominant strains outcompete less abundant ones through superior growth or adhesion to host epithelial cells. This research will provide critical insights into rUTI pathogenesis, laying the groundwork for microbiota-directed preventive and therapeutic strategies to reduce reliance on antibiotics in managing rUTI in humans and animals.

• DFG Programme: Fellowship
• International Connection: Denmark
• Host: Professor Dr. Luca Guardabassi