Abstract

Purpose/Background

Carbapenems remain critical for treating infections caused by multidrug-resistant gram-negative organisms. While meropenem has broader spectrum of activity, ertapenem offers narrower coverage and remains reliable against ESBL-producing Enterobacterales. Previously restricted to one-time dose at day of discharge, ertapenem use was expanded system-wide for appropriate inpatient therapy under updated restriction criteria implemented in June 2025. The purpose of this study is to evaluate changes in ertapenem and meropenem utilization across a multi-hospital system following this modification and to assess its impact on carbapenem prescribing patterns and antimicrobial stewardship practices.

Methodology

This multi-center, retrospective quality improvement project included five hospitals (1,831 combined number of beds) and evaluated adult patients who received at least one dose of ertapenem or meropenem during November 2024 (pre-restriction period) and November 2025 (post-restriction period). Patients were excluded if pregnant or had documented refusal of ertapenem or meropenem. The primary outcome was carbapenem duration of therapy (DOT) in days. Secondary outcomes included (1) ertapenem, meropenem, and cumulative DOTs, (2) hospital length of stay (LOS) for intensive care unit (ICU) and non-ICU patients, (3) time from first carbapenem dose to discharge in hours, (4) 30-day all-cause in-hospital mortality, and (5) 30-day infection-related readmission. Descriptive statistics were used to summarize baseline characteristics. Continuous variables with non-normal distribution were reported as median and interquartile range (IQR) and compared using the Mann–Whitney U test. Categorical variables were summarized as frequencies and percentages and compared using chi-square or Fisher’s exact test. A p-value < 0.05 was considered statistically significant. This study was deemed IRB-exempt.

Results

Of 301 patients screened, 300 met inclusion criteria after exclusion of one patient aged < 18 years. Fifty patients per group were included in each drug arm during the pre‑restriction period and 100 per group during the post‑restriction period. In the post‑restriction period, intensivists more frequently initiated meropenem (11% vs 3%), whereas Infectious Diseases providers more frequently initiated ertapenem (77% vs 38%); baseline characteristics were otherwise similar. Median total carbapenem days of therapy (DOT) decreased from 6 days (IQR 4–8) pre‑restriction to 5 days (IQR 3–7) post‑restriction (p=0.049). Median ertapenem DOT increased from 1 day (IQR 1–2) to 3 days (IQR 2–6) (p< 0.001), while median meropenem DOT decreased from 7 days (IQR 4–8) to 4 days (IQR 2–7) (p< 0.001). Cumulative ertapenem DOT increased from 87 to 408 days, and cumulative meropenem DOT increased from 353 days to 553 days. Median time from first carbapenem dose to discharge increased for ertapenem (65 hours [IQR 28–121] vs 96 hours [IQR 64–165], p=0.002) and decreased for meropenem (183 hours [IQR 116–289] vs 122 hours [IQR 74–255], p=0.045). Among non-ICU patients, LOS was shorter with ertapenem than meropenem in the pre-restriction period (4 days [IQR 3-6] vs 8 days [IQR 5-12]) but was similar post-restriction (5 days [IQR 3-7] ertapenem vs 5 days [IQR 4-9] meropenem). ICU LOS remained unchanged across periods for both agents (11 vs 12 days for ertapenem, 12 vs 12 days for meropenem). Thirty-day infection-related readmissions were unchanged for ertapenem (18% vs 14%, p=0.631) but decreased for meropenem (28% vs 14%, p = 0.047). Thirty-day all-cause in-hospital mortality occurred only among ICU patients and did not differ across periods for either agent (2% vs 2% ertapenem, p=0.404; 12% vs 14% meropenem, p=1.000).

Conclusion

Modification of acute-care ertapenem restriction criteria was associated with a one-day reduction in median carbapenem duration of therapy and a shift toward increased inpatient ertapenem use. Meropenem continued to be used in higher-acuity patients.

Publication Date

Spring 5-14-2026

Presented At:

Florida Residency Conference (FRC)

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