Aerococcus mictus as a cause of feline urinary tract infection: a case report.

BACKGROUND: Bacterial urinary tract infections (UTIs) are a noteworthy cause of lower urinary tract disease both in humans and companion animals, especially in patients with systemic comorbidities or underlying anatomical or functional urinary tract abnormalities. Aerococcus species are increasingly recognised as opportunistic uropathogens in human medicine; however, their role in UTIs in companion animals remains poorly characterised. CASE PRESENTATION: The case of a neutered male European Shorthair cat with a history of antepubic urethrostomy and recurrent lower urinary tract signs, in which urine culture yielded a pure growth of Aerococcus mictus, is herein described. Species identification was achieved by whole-genome sequencing, which underscores the value of modern diagnostic tools in recognizing organisms that are often misclassified by conventional methods. The cat was successfully treated with targeted antimicrobial therapy. CONCLUSIONS: To the best of our knowledge, this is the first reported case of A. mictus as a causative agent of UTI in a cat, supporting its potential role as an opportunistic uropathogen in companion animals, highlighting the risk of misidentification among closely related Aerococcus species, and emphasizing the need for updated MALDI-TOF reference databases in veterinary microbiology.