MICROBIOLOGICAL ETIOLOGY AND ANTIBIOTIC RESISTANCE PATTERNS OF LOWER URINARY TRACT INFECTIONS IN PATIENTS ATTENDING THE NEPHROLOGY AND UROLOGY OUTPATIENT CLINIC AT BACH MAI HOSPITAL

Objective: To describe clinical characteristics, microbiological etiology, and antimicrobial susceptibility patterns of pathogens causing lower urinary tract infections (UTIs) at the Nephrology–Urology Outpatient Clinic, Bach Mai Hospital. Methods: A combined retrospective descriptive study was conducted from September 2024 to April 2026. A total of 499 patients diagnosed with lower UTI were included. Results: Among 499 patients, 85,8% were female, and the most affected age group was >60 years (33,1%). The most common symptoms were dysuria (73,3%), urinary frequency (32,8%), and hematuria (24,2%). Urine culture positivity was 71,1%. Escherichia coli was the predominant pathogen (76,1%), followed by Staphylococcus saprophyticus (5,8%), Proteus mirabilis (4,7%), and Klebsiella pneumoniae (4,2%). ESBL-producing strains were identified in 15,3% of E. coli and 20,0% of K. pneumoniae. Gram-negative bacteria showed high susceptibility to carbapenems, fosfomycin, amikacin, and β-lactam/β-lactamase inhibitor combinations, but high resistance to quinolones, cephalosporins, and ampicillin. Antibiotic therapy was modified in 55,14% of 249 patients at first follow-up after empirical treatment. Conclusions: Lower UTIs predominantly affect women and elderly patients. E. coli remains the leading causative organism with a notable proportion of ESBL-producing strains. High resistance to commonly used antibiotics and frequent modification of empirical therapy highlight the importance of urine culture and antimicrobial susceptibility testing to optimize treatment strategies.