Anti-Acinetobacter baumannii single-chain variable fragments provide therapeutic efficacy in an immunocompromised mouse pneumonia model

Background: The emergence of carbapenem-resistant and extensively drug-resistant Acinetobacter baumannii as well as inadequate effective antibiotics calls for an urgent effort to find new antibacterial agents. The therapeutic efficacy of two human scFvs, EB211 and EB279, showing growth inhibitory activity against A. baumannii in vitro , was investigated in immunocompromised mice with A. baumannii pneumonia. Results The data revealed that infected mice treated with EB211, EB279, and a cocktail of two scFvs showed better survival, reduced bacterial load in the lungs, and no marked pathological abnormalities in the kidneys, liver, and lungs when compared to the control groups receiving normal saline or an irrelevant scFv. Conclusions These results suggest that the scFvs with direct growth inhibitory activity could lead to promising outcomes in immunosuppressed patients with A. baumannii infection.