Abstract

Purpose
This study aimed to report antimicrobial resistance (AMR) patterns among patients with complicated urinary tract infection (cUTI) using data from the Korean Antimicrobial Resistance Monitoring System (KARMS). Materials and Methods: In this prospective, multicenter, observational surveillance study, data from patients diagnosed with cUTI between January 2023 and September 2025 were retrieved from the KARMS database. Demographic characteristics, uropathogen distribution, and antimicrobial susceptibility profiles of representative pathogens were analyzed.
Results
Data from a total of 698 patients were collected in the KARMS database. The mean patient age was 68.94±15.95 years. The numbers of patients with healthcare-associated UTI and recurrent UTI were 171 (24.5%) and 240 (34.4%), respectively. Escherichia coli was the most frequently identified uropathogen (n=356, 51.1%). Regarding antimicrobial susceptibility, 92.9% of isolates were susceptible to fosfomycin, 75.5% to nitrofurantoin, 47.2% to ciprofloxacin, 63.3% to cefotaxime, 80.6% to piperacillin/tazobactam, and 98.8% to ertapenem. The rate of extended-spectrum beta-lactamase positivity was 45.2% (166 of 367) and was significantly higher in pyelonephritis and urosepsis (62.3% and 62.5%, p=0.002), healthcare-associated UTI (58.6%, p=0.040), and recurrent cUTI (53.2%, p=0.028). Fluoroquinolone resistance was significantly more common in female patients (49.1%, p=0.021) and in healthcare-associated UTI (57.9%, p=0.014). Piperacillin/tazobactam resistance was significantly higher in patients with urosepsis (37.0%, p=0.004), in tertiary hospitals (17.2%, p=0.019), and in healthcare-associated UTI (26.4%, p=0.001). In addition, third-generation cephalosporin resistance was significantly higher in secondary hospitals than in tertiary hospitals (43.5% vs. 33.3%, p=0.041).
Conclusions
These data provide current information on uropathogen distribution and AMR patterns in cUTI in South Korea. Continued surveillance and ongoing data accumulation through KARMS will support evidence-based strategies for optimal antimicrobial therapy and AMR mitigation.

• Keywords: Urinary tract infection, Republic of Korea, Antibiotic resistance