Infectious complications remain a major concern in endoscopic stone surgery, particularly in patients presenting with bacteriuria. Postoperative infections, including febrile urinary tract infections and urosepsis, significantly contribute to patient morbidity, prolong hospital stay, and increase healthcare costs. While prophylactic antibiotic use is well established in cases with sterile urine, there is a lack of consensus regarding optimal timing and duration of antibiotic therapy in patients with asymptomatic or clinically significant bacteriuria. This study aimed to assess the impact of preoperative bacteriuria on postoperative infectious outcomes and to evaluate the effectiveness of a tiered antibiotic prophylaxis protocol based on urine culture and bacterial load.

A retrospective cohort analysis included 211 patients who underwent endoscopic treatment of upper urinary tract stones between January and July 2023. Patients were stratified based on preoperative urine culture into three groups: sterile urine, low-titer bacteriuria (<10⁵ CFU/mL), and high-titer bacteriuria (≥10⁵ CFU/mL). Antibiotic prophylaxis was administered accordingly: a single preoperative dose for sterile urine, a 3-day course for low-titer bacteriuria, and a 7-day course for high-titer bacteriuria, followed by repeated urine culture prior to surgery. The primary endpoint was the incidence of postoperative hyperthermia, used as a clinical marker of infection.

Sterile urine cultures were confirmed in 152 patients (72%), while 59 patients (28%) had preoperative bacteriuria. Among these, 31 patients (14.7%) had low-titer and 28 (13.3%) had high-titer bacteriuria. After extended antibiotic therapy, sterility was achieved in 22 of 28 patients (78.6%) with high-titer bacteriuria. Ultimately, 37 patients with residual bacteriuria underwent surgery. Postoperative hyperthermia was observed in 17 cases (8.1%), more frequently among patients with bacteriuria (16.2%) than those with sterile urine (6.3%, p = 0.087). Multivariate logistic regression identified bacteriuria as a significant independent predictor of postoperative hyperthermia (OR = 4.75, 95% CI [1.222; 18.803], p = 0.023). Other parameters, including sex, age, BMI, diabetes, stone volume, and surgical time, were not statistically associated with infection risk (p > 0.05).

Preoperative bacteriuria is a significant risk factor for postoperative infectious complications in patients undergoing endoscopic stone surgery. A stratified antibiotic prophylaxis protocol tailored to bacterial load effectively reduced the incidence of infection. Specifically, a 7-day regimen for high-titer and a 3-day regimen for low-titer bacteriuria were shown to improve preoperative urine sterility and postoperative outcomes. These findings support a personalized approach to antibiotic management, promoting patient safety while mitigating the risks of overtreatment and antimicrobial resistance.