Gentamicin-Augmented Intrarenal Irrigation During Percutaneous Nephrolithotomy Reduces 30-Day Infectious Complications and Eliminates Pyelonephritis and Sepsis: A 1:2 Matched Cohort Study

Purpose: To evaluate whether gentamicin-augmented intrarenal irrigation during percutaneous nephrolithotomy (PCNL) was associated with fewer 30-day urinary infectious complications. Materials and Methods: Single-center retrospective 1:2 matched cohort study of adults undergoing PCNL between January 2020 and June 2026. One hundred thirteen patients receiving gentamicin-augmented irrigation (80 mg per 3-L bag of 0.9% saline) were propensity-score matched to 226 saline controls on age, sex, body mass index, Charlson Comorbidity Index, ASA score, diabetes, and a pre-existing nephrostomy tube. The primary endpoint was a 30-day composite of symptomatic urinary tract infection with culture >1,000 CFU/mL, febrile UTI or pyelonephritis, or sepsis. A [&ge;] 100,000 CFU/mL composite was a prespecified sensitivity endpoint and asymptomatic bacteriuria a prespecified negative control. Results: The primary composite infection outcome occurred in 3/113 (2.7%) versus 33/226 (14.6%) (risk difference -11.9%, 95% CI -17.4 to -5.6; NNT=8; p=0.001), and at [&ge;] 100,000 CFU in 1.8% versus 13.7% (p<0.001). Febrile UTI/pyelonephritis occurred in 0% versus 6.2% (p=0.006) and sepsis in 0% versus 4.0% (p=0.03), respectively. All events in the intervention arm were culture-defined UTI without fever or organ dysfunction. SIRS occurred in 31.9% versus 54.4% (p<0.001), while asymptomatic bacteriuria did not differ (2.7% versus 3.5%, p=0.758), respectively. Gentamicin remained protective after adjustment for demographic and stone characteristics (odds ratio 0.17, 95% CI 0.04-0.60; p=0.005). Acute kidney injury by postoperative day 1 occurred in 17.0% versus 17.6% (p=1.0). Conclusions: Gentamicin-augmented intrarenal irrigation during PCNL was associated with fewer 30-day urinary infectious complications. Additionally, among treated patients meeting the primary outcome, there were no febrile or septic events, indicating a reduced severity of infectious complications when they did occur.