Antimicrobial Resistance Rates and Risk Factors for Extended-Spectrum Beta-Lactamase-Producing Escherichia coli-Associated Urinary Tract Infections in Older Outpatients in East Anatolia from 2011 - 2019

Background: Community-acquired urinary tract infection is among the most common infections in older adults. Regardless of age, the most frequently detected causative microorganism is Escherichia coli. In parallel with the increase in antibiotic use, the frequency of community-acquired extended-spectrum beta-lactamase-producing E. coli (ESBL-E. coli) has reached critical levels. The use of empirical antibiotic therapy is determined by assessing patient-based risk factors. Therefore, knowing the risk factors and the frequency of antimicrobial resistance can guide the treatment to shape the treatment. Objectives: This study aimed to determine the risks and resistance frequencies to guide the empirical treatment selection for ESBL-E. coli-associated urinary tract infection (UTI) in elderly patients. Methods: This study is a retrospective cohort study. It was carried out between 2011 - 2019. Escherichia coli growth of ≥ 105 colony-forming units (cfu)/mL in urine culture was included in 815 patients aged 65 and over who applied to outpatient clinics. Results: Two hundred and sixty (31.9%) of the patients had ESBL-E. coli. In ESBL-E. coli, antimicrobial resistance rates were highest (100%) for penicillins + β-lactamase inhibitors. The lowest resistance rates were determined for carbapenems, aminoglycosides, phosphonic acid, and nitrofurantoins. Risk factors for ESBL-producing bacteria were determined. These were the presence of benign prostatic hypertrophy, antibiotic use in the last three months, history of UTI in the last year, urinary catheter uses in the last year, male gender, and hospitalization in the last year (P < 0.05). The only independent risk factor was a history of UTI in the last year, which increased the risk of ESBL by 2.8 times. Conclusions: Carbapenems can be chosen as parenteral options, and phosphonic acids and nitrofurantoin as oral options for empirical antibiotic treatment, especially in patients with a history of UTI in the past year.