Prevalence, Determinants, and Temporal Dynamics of Multidrug-Resistant Gram-Negative Bacilli in Urinary Tract Infection Patients from Central Portugal (2018–2022)

Background: Multidrug-resistant (MDR) Gram-negative bacilli (GNBs) significantly compromise the effective management of urinary tract infections (UTIs) worldwide. As antimicrobial resistance varies across regions, locally tailored data are essential to guide empirical therapy. This study investigated the prevalence, determinants, and temporal dynamics of MDR GNBs in UTI patients from Central Portugal between 2018 and 2022. Methods: We conducted a retrospective observational study at a hospital center in Central Portugal, analyzing data from 2018 to 2022. Data from 5194 UTI patients with GNB-positive cultures were analyzed. Binary logistic regression was used to identify determinants of MDR GNBs, defined as resistance to ≥1 agent in ≥3 antibiotic classes. Results: The study population had a mean age of 64.5 ± 25.3 years, and females represented two-thirds of the sample (67.0%). The overall prevalence of MDR GNBs was 35.8%. Advanced age (≥75 years), male sex, and specific treatment contexts—particularly day treatment and laboratory-only cases—were independently associated with MDR. SBL-producing Enterobacterales and non-fermenting GNBs showed the highest risk levels. Conclusions: MDR GNBs are highly prevalent among UTI patients in Central Portugal, and their increasing trend—particularly in 2022—highlights an urgent need for strengthened surveillance and updated empirical treatment strategies. The observed temporal increase highlights the urgent need for strengthened regional surveillance and updated empirical treatment guidelines.