Comparative characteristic of antimicrobial resistance in geriatric hospital: a retrospective cohort study

Background and aims: To examine antimicrobial resistance of commonly isolated pathogens in elderly hospitalized patients. Methods: Data regarding all clinically significant isolates from blood and urine cultures of patients admitted to a multilevel geriatric hospital during March 2015 to April 2016 were collected. Antimicrobial susceptibility testing was performed according to Clinical and Laboratory Standard Institute guidelines. Results: Escherichia coli, Proteus mirabilis, and Klebsiella pneumoniae were the most common isolates, with proportions of extended spectrum beta-lactamase positivity of 60, 40, and 61% respectively. Adjusted logistic regression models indicated that resistance of Escherichia coli to ceftriaxone [odds ratio (OR) 2.8, 95% confidence interval (CI) 1.5–5.1], ceftazidime (OR 2.8, 95% CI 1.5–5.1), ciprofloxacin (OR 2.2, 95% CI 1.2–4.0), amoxicillin/clavulanic acid (OR 2.3, 95% CI 1.2–4.3), and trimethoprim/sulfamethoxazole (OR 2.4, 95% CI 1.4–4.3) was significantly higher in skilled nursing wards than in acute geriatric wards. Resistance of Proteus mirabilis to ceftriaxone (OR 3.1, 95% CI 1.5–6.4) and Klebsiella pneumoniae to ciprofloxacin (OR 3.2, 95% CI 1.3–7.9) was significantly higher in skilled nursing wards than in acute wards. Conclusions and discussion: Antimicrobial resistance was found to be high in a multilevel geriatric hospital, especially in skilled nursing wards. These findings call for rethinking of the empirical antimicrobial therapy and of the efforts for prevention of nosocomial infection.