Rare Urinary Tract Infection with Streptococcus Mitis/Oralis following Ureteroscopy in a Patient with Urinary Stones and Ureteral Stenosis

Abstract

Introduction Streptococcus mitis/oralis are species of the Viridans group streptococci. Viridans group streptococci (VGS) are a group of anaerobic Gram-positive bacteria with alpha-hemolytic characteristics that are commonly found in the mouth, upper respiratory tract, and gastrointestinal system. VGS is not a common pathogen in urinary tract infections. Ureteroscopy and percutaneous nephrolithotomy (PCNL) are standard treatments for urinary stones. Although these procedures are generally safe, post-operative infections remain a common complication. Case presentation Case Presentation: A 49-year-old female presented with bilateral flank pain. Based on the patient's symptoms and examinations, paraclinical investigations were performed, which showed bilateral ureteral stones and elevated serum creatinine levels (Cr=1.88). The patient underwent ureteroscopy, which resulted in the left ureteral stones being broken and removed. However, right ureteroscopy was unsuccessful due to kinking and severe stenosis. Bilateral double-J stent placement and right nephrostomy were performed. One month later, the patient's double-J stents were removed, and the left ureter was clear on ureteroscopy. Right ureteroscopy showed urinary stones and a large amount of bezoar in the proximal ureter and right renal pelvis. The patient finally underwent PCNL. Conclusions Although Streptococcus mitis/oralis is an uncommon cause of UTIs after ureteroscopy, it should be considered a potential pathogen in patients with multiple risk factors such as urinary catheterization, prolonged urinary obstruction, and multiple urological procedures. Copyright © 2026 Urology Research Center (URC), Tehran University of Medical Sciences.