Changes in Antimicrobial Resistance of Urinary Tract Infections in Adult Patients over a 5-Year Period.

Objectives: We aimed to determine the most common bacteria that cause urinary tract infections (UTIs), the rate of antibiotic resistance of these uropathogens, and the changes in resistance rates over the years for adult patients diagnosed with UTIs.

Methods: We retrospectively reviewed urine cultures and antibiotic susceptibility results of patients >17 years of age from our outpatient clinic between 2014 and 2018. The most common uropathogens and their antibiotic resistance rates were identified in different age groups (18-39, 40-59, and ≥60 years) and with respect to gender and date of admission. In addition, the change in antibiotic resistance of Escherichia coli between 2014 and 2018 was also examined.

Results: A total of 9,556 positive urine cultures were included. The most common uropathogen was E. coli, and its prevalence was higher in females than males (70.6 vs. 53.4%, respectively). The majority of isolates were from patients ≥60 years of age. E. coli resistance was most pronounced for ampicillin (61.56%), followed by trimeth-oprim-sulfamethoxazole (49.80%), amoxicillin-clavulanic acid (34.69%), and cefazolin (30.72%). E. coli resistance to ampicillin, nitrofurantoin, cefepime, ciprofloxacin, fosfomycin, and amoxicillin-clavulanic acid increased significantly with time (all p = 0.001). For E. coli, resistance to ciprofloxacin, one of the most commonly used antibiotics for UTI, increased from 17 to 43% from 2014 to 2018.

Conclusion: Most of the uropathogens displayed high resistance to ampicillin, tri-methoprim-sulfamethoxazole, and amoxicillin-clavulanic acid, and were susceptible to meropenem, ertapenem, and imipenem. Fosfomycin and cefepime were useful in the empirical treatment of community-acquired UTIs. A surprisingly high increase was observed in the resistance of E. coli to antimicrobial agents from 2014 to 2018.