Establishment and optimization of an E. coli urinary tract infection model in Göttingen minipigs with strain recovery and characterization

Introduction Urinary tract infections caused by uropathogenic E. coli (UPEC) affect millions of individuals worldwide. Existing animal models used to study UTI treatment or vaccine efficacy have limitations and cannot accurately predict efficacy in humans. In this study we aimed to establish and optimize an intraurethral UPEC urinary tract infection (UTI) model in Göttingen minipigs with characterization of the strains recovered from the urine. Methods Foley balloon catheters were used to challenge minipigs intraurethrally with UPEC strain UTI89. Urine collected after challenge was plated for bacterial enumeration and recovered bacteria was tested for agglutination and whole genome sequencing. Results Through intraurethral challenge with UTI89, we were able to establish infection for 14 days. Agglutination and whole genome sequencing revealed that 75% of the animals were infected with UTI89 challenge strain, while in 25% of the animals, a different E. coli strain was recovered from urine. Therefore, our results emphasize the need for caution when interpreting bacterial enumeration outcomes from UTI models. Careful verification of strain identity is essential to ensure accurate evaluation of intervention effects with vaccine and antibiotic studies. Discussion Altogether, we describe a novel minipig UTI model using an intraurethral challenge with UPEC strain UTI89 that can be used to assess vaccines and treatment efficacy; and will serve to bridge the gap between preclinical findings and clinical outcomes in humans.