(566) Antimicrobial Exposure and Resistance Patterns in Prolonged Extracorporeal Membrane Oxygenation

Introduction: Extracorporeal Membrane Oxygenation (ECMO) is a life sustaining measure used in select critically ill patients. ECMO runs exceeding 14 days in duration inherently increase the risk for nosocomial infections. Limited data is available describing the antimicrobial exposure patients receive during prolonged ECMO therapy and associated risk for resistance.

Methods: This was a retrospective cohort study performed at two large tertiary academic medical centers within a single health care system from January 1, 2021 to January 1, 2023. Adult patients 18 years of age and older who received at least 14 consecutive days of ECMO therapy were included. The primary outcome was to characterize the antibiotic and antifungal exposure in prolonged ECMO. Secondarily, antimicrobial resistance patterns were described and characterized.

Results: One hundred and thirty-nine patients met inclusion criteria, with most patients receiving venovenous ECMO (100/139, 72%). The average duration of ECMO therapy for the cohort was 44 days (SD 37.65). Most patients had no documented history of antimicrobial resistance but received empiric anti-methicillin resistant Staphylococcus aureus (MRSA) (96%) and / or anti-pseudomonal (94%) antibiotics. Empiric antibiotic exposure greater than 21 cumulative days was associated with subsequent resistant microbiological growth on culture (OR 2.48, 95% CI 1.02-6.01). Targeted antibiotics of any duration, including greater than 21 days, were not associated with increased risk of resistance (OR 1.89, 95% CI 0.87-4.12).

Conclusions: Patients receiving prolonged ECMO therapy within the University of Pennsylvania Health-System generally receive broad spectrum antibiotics. Extended durations (>21 days) of non-targeted antibiotics was associated with developing antimicrobial resistance when compared to targeted antibiotics. Limiting durations of broad antibiotics and tailoring therapy to culture results is key to minimizing development of bacterial resistance for patients receiving prolonged courses of ECMO therapy.