2026 Eastern States Conference

Title: 
Combination therapy for carbapenem-resistant Acinetobacter baumannii infections: what is the optimal regimen?
Authors: 
Hyun Ju Abigail Yoon, PharmD; Patrick Lake, PharmD, BCIDP; Siddharth Swamy, PharmD, BCIDP; Yen-Hong Kuo, PhD; Rani Sebti, MD
Objective: 
Audience members will be able to compare treatment outcomes of various multi-drug regimens for infections due to carbapenem-resistant Acinetobacter baumannii.
Self Assessment Question: 
Which of the following are appropriate treatment options for CRAB infections?
A. Sulbactam-durlobactam plus meropenem
B. Ceftriaxone plus azithromycin
C. Cefepime plus metronidazole
D. Piperacillin-tazobactam plus linezolid
Background: 
The objective of this study was to compare the treatment outcomes of sulbactam-durlobactam- and cefiderocol-based combinations for the treatment of carbapenem-resistant Acinetobacter baumannii (CRAB) infections.
Methods: 
This was a multicenter retrospective study. Patients were included if they were hospitalized between October 2020 and November 2025, had infections due to CRAB, and received one of the following combination antimicrobial regimens as targeted therapy for a minimum of 72 hours. Antimicrobial regimens included sulbactam-durlobactam-based regimens (excluding cefiderocol), and cefiderocol-based regimens (excluding sulbactam-durlobactam). Outcomes were compared in each treatment group. The primary outcome was clinical failure. Clinical failure was defined as in-hospital mortality, an escalation in antimicrobial therapy, or an incomplete duration of therapy. Secondary outcomes included in-hospital mortality, duration of therapy, escalation of therapy, and microbiologic cure (only for bloodstream infections). 
Results:
Of 396 patients screened, 186 were included: 165 in the cefiderocol arm and 21 in the sulbactam-durlobactam arm. Median Charlson Comorbidity Index scores were 6 and 5, respectively, indicating high baseline mortality risk. Pneumonia was the most common infection, followed by bloodstream infections. Cefiderocol monotherapy (67.9%) and sulbactam-durlobactam plus meropenem (61.9%) were the most common regimens. Clinical failure occurred in 20.6% versus 14.3% (p=0.82), respectively. In-hospital mortality was higher in the cefiderocol group (17.6% vs 0%). No significant differences were observed in primary or secondary outcomes.
Conclusion:
There was no significant difference in clinical failure between cefiderocol- and sulbactam-durlobactam-based regimens. However, the cefiderocol arm had a higher rate of in-hospital mortality. Given the mortality imbalance between groups and the predominance of cefiderocol monotherapy, further studies are warranted to evaluate the role of cefiderocol monotherapy versus combination therapy in CRAB infections.