Background: Antibiotic use is one of the major drivers of antimicrobial resistance with RACFs identified as one of the reservoirs for AMR. Real life data on antibiotic use and bacterial resistance patterns is lacking in this setting.
Objectives: The aim of this study was to longitudinally examine and compare trends of antimicrobial resistance (AMR) among urine Escherichia coli (E. coli) isolates and antibiotics frequently used for urinary tract infections (UTIs) in residential aged care facilities (RACFs).
Methods: A total of 11 104 urine E. coli isolates from a private community-based laboratory testing for RACFs and antibiotic dispensing data from pharmacy medication supply data from RACF residents in the Illawarra region (Australia) were analysed between 2016-2018. We did an ecological time-series analysis to estimate the monthly prevalence of UTI antibiotic utilization and proportion of E. coli cases for which the bacteria were resistant to each antibiotic individually, for five different antibiotics (amoxicillin, amoxicillin with clavulanate acid, cephalexin, norfloxacin and trimethoprim).
Results: This study included 3459 unique residents from 20 different RACFs; 8 990 (81%) of E. coli isolates from urine of RACF residents were resistant to one or more antibiotics. Both antibiotic use and resistant E. coli isolates showed variation over time. Results indicate that resistance followed the patterns of antibiotic use for amoxicillin with clavulanate acid, cephalexin, trimethoprim and with the strongest association for norfloxacin that shows both a gap in use and none of the isolates resistant between August 2017 to March 2018.
Conclusions: Our findings indicate that the resistance of E. coli might be driven by antibiotic use in Australian RACFs. Data linkage between medication and pathology data is needed to investigate the magnitude to which antibiotic use drives AMR.
