Abstract Rationale Despite efforts from antibiotic stewardship programs, rates of multidrug-resistant (MDR) organisms continue to rise. For critically ill adults, Pseudomonas aeruginosa frequently causes severe, life-threatening pulmonary infections. The COVID-19 pandemic propagated antibiotic use in Intensive Care Units (ICUs), but its effect on the prevalence of MDRO Pseudomonas aeruginosa remains unknown. Methods Using a federated approach across three U.S. health systems that store data in the Common Longitudinal ICU Format (CLIF) locally, we conducted a retrospective cohort study of adults in ICUs with a Pseudomonas aeruginosa respiratory culture between 2018-2024. Respiratory cultures were collected by expectoration, tracheal aspiration, or broncho-alveolar lavage. Cultures were classified as MDR according to established criteria by the CDC and ECDC. Patient demographics and clinical outcomes were compared between patients with and without any MDR Pseudomonas aeruginosa culture during their hospitalization. To evaluate whether MDR rates differed across healthcare systems, nested linear models were used to test for differences in intercepts and slopes (i.e., trajectories) with system and system-by-time interaction terms. Results A total of 4,975 respiratory cultures with Pseudomonas aeruginosa in 1,948 critically ill adults across 20 hospitals (median age 63.6 IQR 50.5-72.5, 36.9% female, 23.5% non-Hispanic Black), 373 (19.1%) had at least one MDR culture. Patients with MDR cultures were younger (60.7 years vs 64.2 years) and more likely to be admitted to a medical ICU (44.7% vs 35.6%). The distribution of respiratory support, such as tracheal collar (29.0% vs 21.7%), high-flow nasal oxygen (27.0% vs 32.8%), non-invasive mechanical ventilation (22.0% vs 22.7%), invasive mechanical ventilation (85.3% vs 86.0%), varied between patients with and without MDR cultures (p = 0.03). Patients with MDR cultures had longer length of ICU stays (mean 12.5 ± 11.7 days vs 9.2 ± 8.3 days, p 0.01) and similar ICU mortality (14.5% vs 15.1%, p = 0.81). Across all years, MDR rates fluctuated, with a nadir of 15.0% and a peak of 24.4% (Figure 1). Baseline MDR rates in 2018 differed across healthcare systems (p = 0.01), ranging from 15.6% to 21.4%. Longitudinal trajectories of MDR rates from 2018 to 2024 within each healthcare system did not differ (p = 0.76). Conclusions Although the prevalence of MDR Pseudomonas aeruginosa varied between healthcare systems, the rise in antibiotic resistance during the COVID-19 pandemic followed a consistent trend in all settings. Large-scale epidemiological studies are needed to monitor whether rates of MDR return to baseline, and if not, targeted mitigation strategies should be promptly implemented. This abstract is funded by: None
Liu et al. (Fri,) studied this question.