(C-074) The temporal trends of Escherichia coli antimicrobial resistance and antibiotic utilization in Australian Long-Term Care Facilities

Background: Long-term care (LTC) facilities have been identified as potential reservoirs for Escherichia coli (E. coli) AMR, due to high rates of urinary tract infections (UTIs) and frequent antibiotic use among residents. While the association between these two factors is well established, the temporal relationship remains largely unknown.

Objectives: This study investigated trends in E. coli AMR and antibiotic utilization in LTC, focusing on potential temporal relationships.

Methods: A retrospective, longitudinal, ecological analysis was conducted between 31 May 2016 and 31 December 2018. The primary outcomes were the monthly prevalence of E. coli AMR in urine isolates and residents using an antibiotic recommended for the management of UTIs in national treatment guidelines (amoxicillin, amoxicillin with clavulanic acid, cefalexin, norfloxacin, and trimethoprim).

Results: Between 2016 and 2019, 10,835 urine E. coli isolates were tested, and 3,219 residents received one or more medicines. Around one in five isolates were resistant to at least one of the target antibiotics (23.3%). For most antibiotics the temporal relationship between AMR and antibiotic utilization was unclear; however, potential relationships were observed for both trimethoprim and amoxicillin with clavulanic acid. Trimethoprim showed a temporal decrease in both AMR and utilization while amoxicillin with clavulanic acid showed a lag time of approximately four months.

Conclusions: The dynamic nature of AMR demonstrated in this study highlights the need for more up-to-date local surveillance to inform antibiotic choice in this setting.