Document Type
Article
Publication Date
7-17-2025
Keywords
Acinetobacter, sulbactam, CRAB, sulbactam-durlobactam
Abstract
Infections caused by carbapenem-resistant Acinetobacter baumannii-calcoaceticus complex (ABC) are associated with high mortality rates and limited treatment options. This study aims to evaluate the in vitro activity of clinically utilized antimicrobials against a contemporary collection of ABC isolates with a predominant carbapenem-resistant phenotype. Geographically dispersed US medical centers (n =22) provided non-duplicate respiratory and bloodstream ABC isolates for surveillance testing. Antimicrobial susceptibility testing was conducted by broth microdilution and interpreted according to Clinical & Laboratory Standards Institute (CLSI) and Food and Drug Administration (FDA) breakpoints. ABC isolates (n = 523) from respiratory tract (74.4%) and blood (25.6%) sources were recovered from patients (2023–2024). Forty percent were obtained from intensive care unit patients. Carbapenem non-susceptibility was observed in 76.9% of isolates and was more common among respiratory tract cultures. The addition of durlobactam to sulbactam decreased the MIC90 by three-doubling dilutions from 32 to 4 μg/mL, increasing the susceptibility rate to 96.9% from 33.8%. Genome sequencing of sulbactam-durlobactam non-susceptible isolates (16/523; n = 3.1%) revealed MBL and non-enzymatic resistance mechanisms. Cefiderocol inhibited 93.5% and 76.1% of isolates at CLSI and FDA susceptible breakpoints, respectively. Minocycline susceptibility was < 50%, while tigecycline and eravacycline MIC50/90 were 1/2 and 0.5/1 μg/mL, respectively. Sulbactam-durlobactam displayed high activity against sulbactam (95.4%), carbapenem (96.3%), and cefiderocol (95.2%) non-susceptible isolates. Susceptibility rates of clinically utilized antimicrobials against a US collection of ABC isolates ranged from 23% to 97%, with meropenem displaying the lowest rate and sulbactam-durlobactam demonstrating the highest overall rate. Sulbactam-durlobactam activity was preserved against sulbactam, carbapenem, and cefiderocol non-susceptible isolates among respiratory tract and bloodstream isolates.
Publisher Attribution
Copyright © 2025 Buyukyanbolu et al. This is an open-access article distributed under the terms of the Creative Commons Attribution 4.0 International license. Published in Antimicrobial Agents and Chemotherapy.
Recommended Citation
Buyukyanbolu, Ecem; Argotsinger, Jill; Beck, Eric T.; Chamberland, Robin R.; Clark, Andrew E.; Daniels, Anne R.; Liesman, Rachael; Fisher, Mark; Gialanella, Philip; Hand, Jonathan; Harrington, Amanda T.; Humphries, Romney M.; Huse, Holly; Hamilton-Seth, Robert; Hankins, Julia D.; Kufel, Wesley D.; Riddell, Scott W.; Marino, Jamie; Westblade, Lars F.; Mochon, Brian; Narayanan, Navaneeth; Kirn, Thomas J.; Pierce, Virginia M.; Potula, Raghava; Tekle, Tsigereda; Simner, Patricia J.; Tibbetts, Robert J.; Vu, Christine; Abbo, Lilian M.; Martinez, Octavio; Dumm, Rebekah E.; Nicolau, David P.; Asempa, Tomefa E.; and Acinetobacter baumannii Complex National Biorepository (ACNBio) Study Group, "Activity of ampicillin-sulbactam, sulbactam-durlobactam, and comparators against Acinetobacter baumannii-calcoaceticus complex strains isolated from respiratory and bloodstream sources: results from ACNBio study" (2025). Pharmacy Faculty Scholarship. 79.
https://orb.binghamton.edu/pharmacy_fac/79
Creative Commons License
This work is licensed under a Creative Commons Attribution 4.0 International License.
Comments
10.1128/aac.00379-25