Title:
Ertapenem versus cefepime or other carbapenems for the treatment of AmpC-producing organisms
Authors:
Michelle Fuksman, PharmD; Antoinette Acbo, PharmD, BCIDP; Mary McKiever, PharmD; Sarah Valiante, PharmD, BCIDP
Learning Objective:
Compare the efficacy of select beta-lactams for the treatment of infections due to AmpC-producing organisms.
Self-Assessment Question:
Which of the following antibiotics would NOT be appropriate to treat
Enterobacter cloacae bloodstream infection?
- Cefepime
- Imipenem
- Piperacillin-tazobactam
- Ertapenem
Background/Objective:
Ertapenem lacks data for the treatment of AmpC-producing organisms, but it is often used in clinical practice. This study aimed to investigate ertapenem for the treatment of AmpC-producing organisms compared to cefepime and other carbapenems.
Methods:
This retrospective, single center study evaluated ertapenem versus cefepime, meropenem, or imipenem for the treatment of AmpC-producing organisms. This study included adult patients given one of the study drugs as definitive therapy for AmpC-producing organisms from May 26, 2021 to June 30, 2025. Patients were excluded if they were pregnant, treated with over 72 hours of appropriate treatment before definitive therapy, treated with less than 72 hours of definitive therapy, expired within 48 hours of definitive therapy initiation, or if the pathogen was in stool culture only or resistant to definitive treatment. The primary endpoint was 90-day mortality. The secondary endpoints included 30-day mortality, clinical failure, microbiologic failure in patients with a positive blood culture, 30- and 90-day recurrence, and length of stay.
Results:
Across 216 patients, 96 received ertapenem, 86 received cefepime, 11 received imipenem, and 23 received meropenem. Ertapenem compared with cefepime, imipenem, or meropenem was not associated with increased 90-day mortality (22% versus 34%, 45%, and 39%, respectively; p=0.11) or increased 30-day mortality (17% versus 22%, 27%, and 39%, respectively; p=0.12). Microbiologic failure occurred in 1 case in the ertapenem group (1.0%; p>0.99). 30- and 90-day recurrence was comparable between treatments and occurred infrequently. In the meropenem and ertapenem groups, clinical failure (78% and 54% respectively; p=0.21) and median length of hospitalization (30 days and 23 days respectively; p=0.46) were not significantly different.
Conclusion:
Among patients with infections due to AmpC-producing organism(s), this data demonstrated no significant differences in ertapenem’s efficacy compared to cefepime, meropenem, or imipenem-cilastatin.
