Assessment of Factors Contributing to Multidrug Resistance in Urinary Tract Infections: Focus on Carbapenem Resistance

Introduction: Urinary tract infections (UTIs) caused by carbapenem-resistant pathogens are increasingly common and pose serious treatment challenges due to limited antibiotic options and high complication rates. Identifying patients at risk is essential for guiding empirical therapy and improving outcomes. The primary objective of this study was to identify risk factors associated with carbapenem-resistant (CR) UTIs by comparing them with carbapenem-susceptible (CS) UTIs. Secondary objectives included analyzing the types of microorganisms involved in both groups, their antibiotic susceptibility profiles, and the presence of carbapenemase enzymes among CR UTI cases. Method: We conducted a retrospective case-control study involving 127 hospitalized patients with UTIs caused by CR microorganisms and 91 patients with UTIs caused by multidrug-resistant (MDR) strains that retain susceptibility to carbapenems, admitted between 1 October 2023, and 31 March 2025. Results: In univariate analysis, CR UTI patients had significantly higher rates of neoplasia, neurological disorders, urosepsis at admission, septic shock, the presence of urinary catheters at diagnosis, permanent nephrostomy catheters, hospitalizations within the past 180 days, previous antibiotic exposure including carbapenems, and recent urological procedures. Multivariate analysis revealed four independent risk factors for CR UTIs: neoplasia (OR = 2.152; 95% CI: 1.044–4.436; p = 0.038), neurological disorders (OR = 7.427; 95% CI: 2.804–19.674; p < 0.0001), antibiotic use in the previous 180 days (OR = 2.792; 95% CI: 1.487–5.396; p = 0.001), and prior carbapenem treatment OR = 10.313; 95% CI: 1.277–83.248; p = 0.029). Most of the isolated organisms belonged to the Enterobacterales genus, with Klebsiella spp. and Pseudomonas aeruginosa being the most common pathogens in CR UTIs, accounting for over 90% of cases. Among patients tested for carbapenemase production, all but one tested positive for at least one carbapenemase. Conclusions: Neoplasia, neurological disorders, recent antibiotic therapy, and prior carbapenem use were significantly associated with increased risk of developing CR UTIs. Klebsiella spp. and Pseudomonas aeruginosa were the predominant causative organisms, with New Delhi metallo-β-lactamase (NDM) and Klebsiella pneumoniae carbapenemase (KPC) being the most frequently identified resistance mechanisms.