In Vitro Activity of Eravacycline, Aztreonam-Avibactam, and Cefiderocol Against Multidrug-Resistant Gram-Negative Clinical Isolates from a Romanian Tertiary Hospital.
4 affiliations
- 1Department of Microbiology, University of Medicine and Pharmacy, Carol Davila, 020021 Bucharest, Romania.
- 2Clinical Laboratory, Emergency University Hospital, 050098 Bucharest, Romania.
- 3Department of Orthopedics, University of Medicine and Pharmacy, Carol Davila, 020021 Bucharest, Romania.
- 4Department of Orthopedics and Traumatology, Emergency University Hospital, 050098 Bucharest, Romania.
Abstract
Background/objectives
Carbapenem-resistant Gram-negative bacteria-especially NDM- and OXA-48-producing Klebsiella pneumoniae and carbapenem-resistant Acinetobacter baumannii (CRAB)-have limited treatment options, and in vitro data from Eastern Europe on the reserve agents eravacycline, aztreonam-avibactam, and cefiderocol are scarce. We evaluated their in vitro activity against consecutive multidrug-resistant (MDR) Gram-negative isolates from a Romanian tertiary hospital, stratified by species and carbapenemase profile.Methods
Seventy-seven consecutive, non-duplicate MDR Gram-negative isolates were collected over a 12-week period (January-March 2026) at a single tertiary center and tested by gradient diffusion (Liofilchem MIC Test Strip). MTS was used as an exploratory screening method; reference broth microdilution (BMD) remains the standard for categorical susceptibility confirmation. MICs were interpreted using FDA and EUCAST v16.0 breakpoints. Carbapenemases were detected by immunochromatography (18 isolates), and carbapenemase-encoding genes were detected by Xpert Carba-R PCR (40 isolates of K. pneumoniae). Susceptibility is reported with Wilson 95% confidence intervals.Results
K. pneumoniae (n = 51) predominated; NDM+OXA-48 was the most common profile (43.1%), and NDM was present in 64.7%. Eravacycline inhibited 90.2% of K. pneumoniae, and aztreonam-avibactam inhibited 92.2%, both covering all NDM-only isolates (9/9). Cefiderocol inhibited 84.3% of K. pneumoniae overall, but only 6/9 (66.7%) of NDM-only producers versus 20/22 (90.9%) of NDM+OXA-48 co-producers, whereas eravacycline and aztreonam-avibactam remained active against all nine NDM-only isolates. Cefiderocol was the only agent active against P. aeruginosa (91.7%); aztreonam-avibactam showed uniformly high MICs against non-fermenters, and all 10 CRAB isolates had low eravacycline MICs (MIC50 0.064 µg/mL).Conclusions
The three agents were complementary: aztreonam-avibactam and eravacycline covered NDM-producing K. pneumoniae, whereas cefiderocol was less active in vitro; cefiderocol alone covered P. aeruginosa. Because MICs were generated by gradient diffusion, these exploratory benchmarks require confirmation by reference broth microdilution; gradient strips agree well with BMD for aztreonam-avibactam but show weaker, agent-dependent agreement for eravacycline and cefiderocol, so they are not yet a validated substitute across all three agents.
Related
- In Vitro Activity of Aztreonam-Avibactam, Cefiderocol, and Conventional Antimicrobials Against Metallo-β-Lactamase-Producing Gram-Negative Urinary Isolates: A Systematic Review and Local Single-Center Retrospective Evaluation in a Tertiary Care Hospital (2016-2025) and Evaluation of Novel Agents (2021-2025).
- Clinical characteristics, molecular features and in vitro susceptibility to sulbactam-durlobactam, cefiderocol, and eravacycline in NDM-1-producing versus OXA-23-producing carbapenem-resistant Acinetobacter baumannii isolates from children in Guangxi, China.
- Activity of aztreonam–avibactam and comparators against difficult-to-treat resistant Enterobacterales from United States medical centres (2020–24) †
- Ceftazidime-avibactam as a polymyxin-sparing option for multidrug-resistant Gram-negative infections in children: a real-world comparative cohort study.
- From sepsis to necrotizing enterocolitis with appendiceal perforation: a case report of successful salvage therapy with aztreonam–avibactam in an extremely preterm infant with NDM-producing Klebsiella pneumoniae
BibTeX
@article{baicus2026vitro,
title = {{In Vitro Activity of Eravacycline, Aztreonam-Avibactam, and Cefiderocol Against Multidrug-Resistant Gram-Negative Clinical Isolates from a Romanian Tertiary Hospital.}},
author = {Anda Baicus and Valentina Daniela Sisu and Andreia Domnica Tatar and Lore-Dana Barcer and Elena Andreea Birlescu and Monica Dugaesescu and Catalin Florin Cirstoiu},
journal = {Antibiotics (Basel, Switzerland)},
year = {2026},
month = sep,
doi = {10.3390/antibiotics15100942},
url = {https://europepmc.org/article/MED/42938683},
note = {CC BY},
}
RIS
TY - JOUR
TI - In Vitro Activity of Eravacycline, Aztreonam-Avibactam, and Cefiderocol Against Multidrug-Resistant Gram-Negative Clinical Isolates from a Romanian Tertiary Hospital.
AU - Anda Baicus
AU - Valentina Daniela Sisu
AU - Andreia Domnica Tatar
AU - Lore-Dana Barcer
AU - Elena Andreea Birlescu
AU - Monica Dugaesescu
AU - Catalin Florin Cirstoiu
PY - 2026
DA - 2026/09/22
JO - Antibiotics (Basel, Switzerland)
DO - 10.3390/antibiotics15100942
UR - https://europepmc.org/article/MED/42938683
AB - Background/objectives Carbapenem-resistant Gram-negative bacteria-especially NDM- and OXA-48-producing Klebsiella pneumoniae and carbapenem-resistant Acinetobacter baumannii (CRAB)-have limited treatment options, and in vitro data from Eastern Europe on the reserve agents eravacycline, aztreonam-avibactam, and cefiderocol are scarce. We evaluated their in vitro activity against consecutive multidrug-resistant (MDR) Gram-negative isolates from a Romanian tertiary hospital, stratified by species and carbapenemase profile.Methods Seventy-seven consecutive, non-duplicate MDR Gram-negative isolates were collected over a 12-week period (January-March 2026) at a single tertiary center and tested by gradient diffusion (Liofilchem MIC Test Strip). MTS was used as an exploratory screening method; reference broth microdilution (BMD) remains the standard for categorical susceptibility confirmation. MICs were interpreted using FDA and EUCAST v16.0 breakpoints. Carbapenemases were detected by immunochromatography (18 isolates), and carbapenemase-encoding genes were detected by Xpert Carba-R PCR (40 isolates of K. pneumoniae). Susceptibility is reported with Wilson 95% confidence intervals.Results K. pneumoniae (n = 51) predominated; NDM+OXA-48 was the most common profile (43.1%), and NDM was present in 64.7%. Eravacycline inhibited 90.2% of K. pneumoniae, and aztreonam-avibactam inhibited 92.2%, both covering all NDM-only isolates (9/9). Cefiderocol inhibited 84.3% of K. pneumoniae overall, but only 6/9 (66.7%) of NDM-only producers versus 20/22 (90.9%) of NDM+OXA-48 co-producers, whereas eravacycline and aztreonam-avibactam remained active against all nine NDM-only isolates. Cefiderocol was the only agent active against P. aeruginosa (91.7%); aztreonam-avibactam showed uniformly high MICs against non-fermenters, and all 10 CRAB isolates had low eravacycline MICs (MIC50 0.064 µg/mL).Conclusions The three agents were complementary: aztreonam-avibactam and eravacycline covered NDM-producing K. pneumoniae, whereas cefiderocol was less active in vitro; cefiderocol alone covered P. aeruginosa. Because MICs were generated by gradient diffusion, these exploratory benchmarks require confirmation by reference broth microdilution; gradient strips agree well with BMD for aztreonam-avibactam but show weaker, agent-dependent agreement for eravacycline and cefiderocol, so they are not yet a validated substitute across all three agents.
SN - 2079-6382
ER -