# P-1299. Clinical Outcomes of Ertapenem in Critically Ill Patients with Bacteremia Caused by ESBL-Producing Organisms: A Comparison of Normal/elevated and Low Albumin Levels

## TL;DR

This study found that critically ill patients with low albumin levels had higher treatment failure rates when using ertapenem for ESBL bacteremia, but the difference was not statistically significant.

## Contribution

The study evaluates the impact of serum albumin levels on ertapenem treatment outcomes for ESBL bacteremia in critically ill patients.

## Key findings

- Patients with low albumin had more treatment failure with ertapenem, but the difference was not statistically significant.
- Ertapenem monotherapy showed higher treatment failure in low albumin patients compared to normal/elevated albumin patients.
- Using meropenem as lead-in therapy before de-escalating to ertapenem was associated with no treatment failure.

## Abstract

Ertapenem, a highly protein-bound drug, may lead to an increased unbound fraction of drug in those with hypoalbuminemia, resulting in faster metabolism and excretion. Because critically ill patients commonly experience hypoalbuminemia, the IDSA guidance suggests utilizing meropenem over ertapenem. This study evaluated whether serum albumin levels impact clinical outcomes the critically ill treated with ertapenem for bacteremia caused by extended-spectrum beta-lactamase (ESBL) producing organisms.
Baseline CharacteristicsThe study groups were well matched between the low and normal/elevated albumin groups (e.g., age, sex, similar severity of bacteremia, and time to initiation of ertapenem.Primary OutcomesPatients receiving ertapenem in the low albumin group had more treatment failure than normal/albumin, although this was not statistically significant. The numbers were driven by microbiologic failure and relapse.

Baseline Characteristics

The study groups were well matched between the low and normal/elevated albumin groups (e.g., age, sex, similar severity of bacteremia, and time to initiation of ertapenem.

Primary Outcomes

Patients receiving ertapenem in the low albumin group had more treatment failure than normal/albumin, although this was not statistically significant. The numbers were driven by microbiologic failure and relapse.

This IRB-exempt, multi-center, retrospective review of ICU patients with bacteremia with polymerase chain reaction (PCR) detection of CTX-M gene from 2021-2024. Patients were included if ertapenem was initiated within 48 hours of PCR detection and continued for ≥ 2 days. Exclusion criteria included ertapenem resistance, > 48 hours of another carbapenem prior to ertapenem, or discharge/death within 48 hours. Patients were stratified into low albumin and normal/elevated albumin (e.g., < 2.5 g/dL and ≥ 2.5 g/dL). Data collected included demographics, antibiotic use, and laboratory values. The primary outcome was a composite endpoint of treatment failure defined as persistent fever or leukocytosis, microbiological failure/relapse, or escalation of therapy. Secondary outcomes included length of stay (LOS), time to microbiological eradication, and 30-day all-cause in-hospital mortality. Appropriate statistical analysis was performed.Secondary OutcomesThere was no difference in hospital and ICU length of stay in patients with low versus normal/elevated albumin. There was no difference seen in time to microbiological eradication. The 30-day all-cause mortality was higher in then normal/elevated albumin (n = 4 versus none in the low albumin group), but all but 1 patient cleared their bacteremia and had resolution of leukocytosis and fever.Subgroup Analysis - Ertapenem AloneAlthough not statistically significant, there were more treatment failures in the low albumin group, including 2 patient with microbiological relapse and failure.

Secondary Outcomes

There was no difference in hospital and ICU length of stay in patients with low versus normal/elevated albumin. There was no difference seen in time to microbiological eradication. The 30-day all-cause mortality was higher in then normal/elevated albumin (n = 4 versus none in the low albumin group), but all but 1 patient cleared their bacteremia and had resolution of leukocytosis and fever.

Subgroup Analysis - Ertapenem Alone

Although not statistically significant, there were more treatment failures in the low albumin group, including 2 patient with microbiological relapse and failure.

A total of 53 patients were included: 32 in low albumin and 21 in the normal/elevated group. Treatment failure occurred more frequently in the low albumin (53.1% vs. 42.9%, p = 0.46). No differences were seen in hospital or ICU LOS, or time to microbiological eradication. In those receiving ertapenem monotherapy, treatment failure was higher in the low albumin group (65% vs. 38.5%, p = 0.13). When meropenem was used as lead-in therapy, treatment failure was not seen. Study limitations include a small sample size and use of adjunctive therapy.

Among critically ill patients with ESBL bacteremia treated with ertapenem, those with low albumin had numerically higher treatment failure. Ertapenem may remain a viable option in those with hypoalbuminemia if they receive meropenem as lead-in therapy, prior to de-escalation.

All Authors: No reported disclosures