2025 Southeastern Residency Conference

Title: Clinical Outcomes in Patients who Receive Ertapenem vs. Meropenem for Extended Spectrum Beta-Lactamase Infections and Have Hypoalbuminemia

Authors: Kendall Ferrara, Melissa George, Joshua Rumph

Background: There are limited and conflicting data currently available for the treatment of ESBL infections in patients with hypoalbuminemia. The standard approach for patients with ESBL infections is treatment with a carbapenem. Ertapenem, compared to other carbapenems, is highly protein bound. In patients that are hypoalbuminemic and/or critically ill, this leads to an increased free fraction of ertapenem and a significantly decreased half-life. Limited clinical literature has shown a significantly increased risk of mortality, readmission, and length of stay in patients who are hypoalbuminemic and receive ertapenem compared to patients receiving other carbapenems. Based on this data, the Infectious Diseases Society of America (IDSA) Antimicrobial-Resistant (AMR) Guidance document suggests utilizing meropenem or imipenem-cilastatin in patients that are critically ill and/or experiencing hypoalbuminemia for ESBL infections outside of the urinary tract. Historically at East Carolina University (ECU) Health, ertapenem has been more commonly used than meropenem for ESBL infections regardless of clinical status or albumin. This study aims to evaluate the treatment failure of ertapenem compared to meropenem in patients who have ESBL infections and hypoalbuminemia. 

Methods: This was a system-wide, retrospective chart review of hospitalized adult patients at ECU Health with hypoalbuminemia who received ertapenem or meropenem for at least 72 hours and had non-urine cultures positive for ESBL Enterobacterales. Hypoalbuminemia was defined as an albumin ≤2.5 g/dL within 72 hours before or after initiation of antibiotic treatment. SlicerDicer in EPIC and the electronic medical record (EHR) were utilized to identify patients. The primary endpoint was treatment failure defined as a composite of 30-day all-cause mortality and infection related readmission. Secondary outcomes included the individual components of the composite outcome, 90-day all-cause mortality and infection related readmission, and hospital length of stay (LOS). Subanalyses of patients with bacteremia and patients admitted to an intensive care unit (ICU) were also performed.

Results: A total of 156 patients with ESBL infections and hypoalbuminemia were included in the study. Of those included, 104 (66.7%) received ertapenem and 52 (33.3%) received meropenem. Overall, baseline characteristics were similar between groups. There was a statistically significant difference in age (70 vs 63 years old) and weight (78.1 vs 90.6 kg), however, these differences are not clinically significant and the difference in weight may be attributed to our institution’s previous rapid molecular blood culture protocol recommending meropenem in patients with a BMI ≥35 kg/m2. Although patients in the meropenem group had significantly lower albumin levels (2.1 g/dL vs 2.3 g/dL, p = 0.0131), this was not clinically significant. The most common type of culture in both groups was blood (57.7% vs 44.2%). Wound cultures were the second most common (18.3% vs 28.8%). ESBL Escherichia coli was the most frequently isolated organism in both groups (54.8% vs 40.4%). There was no statistically significant difference in the primary outcome of treatment failure between the ertapenem and meropenem groups (34.6% vs 46.2%, p = 0.1682; RR 0.75, 95% CI 0.505-1.113). Secondary outcomes, including 30- and 90-day all-cause mortality and infection-related readmission, also showed no significant differences. Subgroup analyses (ICU, age ≥65, bacteremia) revealed no significant differences but were limited by small sample sizes.

Conclusion: In patients with ESBL infections and hypoalbuminemia, there was no significant difference in treatment failure between ertapenem and meropenem. Although numerical differences favored ertapenem, the study was underpowered to detect a statistical significance. Larger, prospective studies are needed to confirm these findings. 

Contact: Kendall.Ferrara@ecuhealth.org