P-1307. High-dose versus Standard-dose Ampicillin-Sulbactam for Acinetobacter baumannii Infections

TL;DR

This study compared high-dose and standard-dose ampicillin-sulbactam for treating Acinetobacter infections and found no difference in effectiveness.

Contribution

The study provides real-world evidence on the efficacy of high-dose versus standard-dose ampicillin-sulbactam for Acinetobacter infections.

Findings

No statistical difference in treatment success between high-dose and standard-dose ampicillin-sulbactam.

No significant differences in mortality, kidney injury, or resistance development between the two groups.

Most infections were polymicrobial, but combination therapy was consistent across both groups.

Abstract

The 2024 Infectious Diseases Society of America Guidance on the Treatment of Antimicrobial-Resistant Gram-Negative Infections recommends high-dose ampicillin-sulbactam (SAM) as part of combination therapy for carbapenem-resistant Acinetobacter baumannii-calcoaceticus complex (ABC) infections when sulbactam-durlobactam is unavailable. The purpose of this study was to evaluate the safety and efficacy of high-dose SAM (> 9 grams/day of sulbactam) vs. standard-dose SAM (< 9 grams/day of sulbactam) in treating various ABC infections.

This was an IRB-approved, single-center, retrospective cohort study of adult patients admitted to The University of Kansas Health System with an index positive ABC isolate susceptible to SAM that was treated with > 3 days of SAM between 10/2020 and 10/2024. Exclusion criteria included pregnancy, death or discharge to hospice prior to receiving > 3 days of SAM, or repeat ABC isolates within study period. The primary endpoint was meeting both clinical success (improvement of signs/symptoms of index infection per treating physician) and microbiological success (no recurrence of initial/alternative infection with ABC within 30 days after SAM was stopped). Secondary endpoints included 30-day all-cause mortality, hospital readmission, occurrence of acute kidney injury (AKI), Clostridioides difficile infection, and development of antimicrobial resistance.

A total of 240 patients were screened, of which 54 were included in the study. More patients received standard (68.5%) compared to high-dose SAM (31.5%). The most common sources of infection were bone/joint (38.9%), respiratory (22.2%), and bloodstream (16.7%). Carbapenem-resistance was phenotypically present in 26 (48.1%) ABC isolates. Most infections in the standard-dose group were polymicrobial. However, concurrent ABC-targeted combination therapy was the same in both groups. There was no statistical difference in the primary outcome of microbiological and treatment success between the high vs. standard-dose SAM groups (93.3% vs. 87.9%, p = 1.000). No difference in 30-day all-cause mortality, AKI, or development of resistance were identified.

Our study showed no difference in treatment success with standard vs high-dose SAM in various ABC infections.

All Authors: No reported disclosures

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