Antimicrobial activity of sulbactam-durlobactam against <i>Acinetobacter baumannii-calcoaceticus</i> complex strains causing non-respiratory and non-bloodstream infections from the United States (2023–2025)

<i>Acinetobacter baumannii</i> most often causes pneumonia in critically ill patients. However, <i>A. baumannii</i> is also an important cause of a broader range of infections, including skin/wound and urinary tract infections. This study aims to evaluate the <i>in vitro</i> activity of sulbactam-durlobactam and comparator antibiotics, including meropenem and cefiderocol against <i>A. baumannii-calcoaceticus</i> complex isolates from non-respiratory and non-bloodstream sources. Samples included 285 <i>A. baumannii-calcoaceticus</i> complex isolates enriched for carbapenem resistance collected across 17 states in the United States (January 2023-May 2025). Antimicrobial susceptibility tests were conducted by manual broth microdilution and interpreted according to Clinical and Laboratory Standards Institute (CLSI) and Food and Drug Administration (FDA) (cefiderocol) standards. <i>A. baumannii</i> complex isolates were primarily cultured from skin/wound (58.6%), urinary tract (31.6%), and other sources (9.8%), including cerebrospinal and peritoneal fluid. Carbapenem resistance was observed in approximately 70% of isolates and more common among skin/wound cultures. Sulbactam-durlobactam was observed to be highly active (96.9% susceptible [S]; MIC<sub>90</sub> 4 mg/L) and demonstrated greater activity than sulbactam (37.9% S; MIC<sub>90</sub> 32 mg/L). Sulbactam-durlobactam also displayed high susceptibility rates across isolate sources, ranging from 96.4 (skin/wound) to 97.8% (urine). Cefiderocol demonstrated similar <i>in vitro</i> activity across culture sources and patient location, inhibiting >90 and >80% of isolates at CLSI and FDA susceptible breakpoints, respectively. Minocycline susceptibility was 69.1%, while tigecycline and eravacycline MICs<sub>50/90</sub> were 1/4 and 0.5/1 mg/L, respectively. The observed data are consistent with results from surveillance studies among respiratory and bloodstream isolates and show that sulbactam-durlobactam demonstrates potent <i>in vitro</i> activity against clinical <i>A. baumannii</i> complex isolates from a variety of culture sources.IMPORTANCE<i>Acinetobacter baumannii</i> is a difficult-to-treat pathogen that often affects hospitalized patients and is known for a high level of multi-drug resistance. While commonly associated with pneumonia, it also causes infections in wounds, the urinary tract, and other parts of the body. This study shows that sulbactam-durlobactam is highly effective against <i>A. baumannii</i> from various infection sites. The results are important because they can inform clinicians on the susceptibility profiles of <i>A. baumannii</i> from a variety of infection sources, not just lung and bloodstream. As new antibiotics come onto the market, it is important to continuously assess resistance patterns to inform patient and system-wide health decisions.

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Journal
Microbiology Spectrum
Published
2026-03-23
DOI
https://doi.org/10.1128/spectrum.03289-25
Primary Topic
Antibiotic Resistance in Bacteria
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article
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article

Antimicrobial activity of sulbactam-durlobactam against Acinetobacter baumannii-calcoaceticus complex strains causing non-respiratory and non-bloodstream infections from the United States (2023–2025)

Virginia Pierce, Jill Argotsinger, Daniel V. Zurawski, Manohar B. Mutnal et al.
Microbiology Spectrum
Antibiotic Resistance in Bacteria
article

Antimicrobial activity of sulbactam-durlobactam against Acinetobacter baumannii-calcoaceticus complex strains causing non-respiratory and non-bloodstream infections from the United States (2023–2025)

Virginia Pierce, Jill Argotsinger, Daniel V. Zurawski, Manohar B. Mutnal, Scott W. Riddell, Rebekah E. Dumm, Julia D. Hankins, Anne R Daniels, Violeta A. Chávez, Romney M. Humphries, Robin R. Chamberland, Hossein Salimnia, Holly Huse, Raghava Potula, Rachael M. Liesman, Christine Vu, Tomefa E. Asempa, Eric T. Beck, Erik Munson, Paulette Pinargote, Meera Mehta, Ryan Demkowicz, Timothy C Jenkins, Jonathan Hand, Mark A. Fisher, Elizabeth A Cyr, Philip Gialanella, Amanda Harrington, Robert Hamilton-Seth, Ayesha Khan, On behalf of the Acinetobacter baumannii Complex National Biorepository (ACNBio) Study Group, Andrew E. Clark, Wesley D. Kufel, Robert J. Tibbetts, Octavio Martinez, Tsigereda Tekle, Jennifer Bowling, David P. Nicolau, A. Brian Mochon, Lilian M. Abbo, Patricia J. Simner
article en

Abstract

<i>Acinetobacter baumannii</i> most often causes pneumonia in critically ill patients. However, <i>A. baumannii</i> is also an important cause of a broader range of infections, including skin/wound and urinary tract infections. This study aims to evaluate the <i>in vitro</i> activity of sulbactam-durlobactam and comparator antibiotics, including meropenem and cefiderocol against <i>A. baumannii-calcoaceticus</i> complex isolates from non-respiratory and non-bloodstream sources. Samples included 285 <i>A. baumannii-calcoaceticus</i> complex isolates enriched for carbapenem resistance collected across 17 states in the United States (January 2023-May 2025). Antimicrobial susceptibility tests were conducted by manual broth microdilution and interpreted according to Clinical and Laboratory Standards Institute (CLSI) and Food and Drug Administration (FDA) (cefiderocol) standards. <i>A. baumannii</i> complex isolates were primarily cultured from skin/wound (58.6%), urinary tract (31.6%), and other sources (9.8%), including cerebrospinal and peritoneal fluid. Carbapenem resistance was observed in approximately 70% of isolates and more common among skin/wound cultures. Sulbactam-durlobactam was observed to be highly active (96.9% susceptible [S]; MIC<sub>90</sub> 4 mg/L) and demonstrated greater activity than sulbactam (37.9% S; MIC<sub>90</sub> 32 mg/L). Sulbactam-durlobactam also displayed high susceptibility rates across isolate sources, ranging from 96.4 (skin/wound) to 97.8% (urine). Cefiderocol demonstrated similar <i>in vitro</i> activity across culture sources and patient location, inhibiting >90 and >80% of isolates at CLSI and FDA susceptible breakpoints, respectively. Minocycline susceptibility was 69.1%, while tigecycline and eravacycline MICs<sub>50/90</sub> were 1/4 and 0.5/1 mg/L, respectively. The observed data are consistent with results from surveillance studies among respiratory and bloodstream isolates and show that sulbactam-durlobactam demonstrates potent <i>in vitro</i> activity against clinical <i>A. baumannii</i> complex isolates from a variety of culture sources.IMPORTANCE<i>Acinetobacter baumannii</i> is a difficult-to-treat pathogen that often affects hospitalized patients and is known for a high level of multi-drug resistance. While commonly associated with pneumonia, it also causes infections in wounds, the urinary tract, and other parts of the body. This study shows that sulbactam-durlobactam is highly effective against <i>A. baumannii</i> from various infection sites. The results are important because they can inform clinicians on the susceptibility profiles of <i>A. baumannii</i> from a variety of infection sources, not just lung and bloodstream. As new antibiotics come onto the market, it is important to continuously assess resistance patterns to inform patient and system-wide health decisions.

Microbiology Spectrum
Marquette University (US), West Virginia University (US), Binghamton University (US), Hospital Authority (HK), Albert Einstein College of Medicine (US), Hartford Hospital (US), Loyola University Medical Center (US), Froedtert Hospital (US), State University of New York (US), Montefiore Medical Center (US), Ochsner Health System (US), University of Arizona (US), Johns Hopkins University (US), University of Miami (US), Henry Ford Health System (US), Wayne State University (US), SUNY Upstate Medical University (US), Medical College of Wisconsin (US), University of Utah (US), Quest University Canada (CA), University of Michigan (US), Ochsner Medical Center (US), Johns Hopkins Medicine (US), University Health System (US), Advocate Lutheran General Hospital (US), Banner Health (US), West Virginia University Hospitals (US), Jackson Health System (US), RF Laboratories (United States) (US), Baylor Scott & White Medical Center - Temple (US), Upstate University Hospital (US), Medical Diagnostic Laboratories (United States) (US), UCLouvain Saint-Louis Brussels (BE), Temple University Health System (US), University Pathologists (US), University of Kansas Medical Center (US), UC Irvine Health (US), Health and Hospital Corporation (US), Baylor Scott & White Health (US), Baylor Scott and White Hillcrest Medical Center (US), Baylor Scott & White All Saints Medical Center (US), Harbor–UCLA Medical Center (US), Albany Medical Center Hospital (US), The University of Texas Southwestern Medical Center (US), Vanderbilt University Medical Center (US), The University of Texas Health Science Center at Houston (US)
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Antibiotic Resistance in Bacteria
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