Not Your Usual Culprit: Relapsing Salmonella enterica Serovar Infantis Urinary Tract Infection.

Urinary tract infection due to Salmonella enterica serovar Infantis (S. Infantis) is exceptionally rare and typically linked to host vulnerabilities. We report a case of a woman in her 60s with metastatic renal cancer, diabetes, chronic kidney disease, and prior splenectomy who developed three episodes of UTI within a year. Repeated urine cultures grew S. Infantis, and whole-genome sequencing confirmed relapse from intestinal colonization. After sequential short antibiotic courses, sustained resolution followed a seven-day regimen combined with reinforced pet-related hygiene measures. This case highlights the importance of considering unusual uropathogens, using genomic tools to confirm persistence, and addressing potential zoonotic reservoirs.