In vitro activity of imipenem-relebactam alone and in combination with fosfomycin against carbapenem-resistant gram-negative pathogens

• Published in: Diagnostic microbiology and infectious disease 2022-07, Vol.103 (3), p.115712-115712, Article 115712
• Main Authors: Xu, Chunquan, Chen, Tao, Zhang, Siqin, Zhou, Cui, Liao, Wenli, Fang, Renchi, Chen, Lijiang, Zhou, Tieli
• Format: Article
• Language: English
• Subjects: carbapenem-resistant Gram-negative bacteria; fosfomycin; imipenem-relebactam
• ISSN: 0732-8893; 1879-0070
• DOI: 10.1016/j.diagmicrobio.2022.115712

The aim of this study was to investigate in vitro activity of imipenem-relebactam alone and in combination with fosfomycin against carbapenem-resistant Gram-negative pathogens. A total of 100 Gram-negative bacteria resistant to carbapenem were collected. Among collected 25 carbapenem-resistant Klebsiella pneumoniae strains, 24 (96%) were KPC producers and none of them displayed NDM-1, NDM-5, and IMP carbapenemase. Among 25 carbapenem-resistant Escherichia coli strains, 3(12%), 1(4%), 17(68%), 25(100%) and 20(80%) harbored KPC, NDM-1, NDM-5, ESBLs, and membrane porin OmpC or OmpF mutations, respectively. Among all the carbapenem-resistant strains, 40% (40/100) were resistant to imipenem-relebactam. The FICI revealed the synergistic (60%, 6/10) and additive (40%, 4/10) effects of imipenem-relebactam in combination with fosfomycin, wherein synergistic activity was found against all tested Klebsiella pneumoniae and Acinetobacter baumannii. Imipenem-relebactam may be a new alternative for carbapenem-resistant Gram-negative pathogens infections and the combination of imipenem-relebactam and fosfomycin warrants further exploration.