The rise of carbapenem-resistant Acinetobacter baumannii (CRAB) presents significant challenges in clinical management and has been identified by the World Health Organization as a priority pathogen requiring new antibiotic strategies. In our previous study, the novel antimicrobial peptide Cec4 demonstrated notable efficacy in reducing clinical CRAB biofilms, yet its underlying mechanism remains unclear. To assess the therapeutic potential of Cec4, it is essential to investigate how it disrupts mature biofilms.Transcriptomic analysis was employed to identify key genes associated with CRAB biofilm reduction by Cec4. Based on bioinformatic findings, the CRISPR-Cas9 system was used to generate gene deletion strains, and the pYMAb2 plasmid facilitated the creation of complementation strains. The involvement of these genes in Cec4-mediated biofilm disruption was then evaluated using crystal violet staining, podocyte staining, laser confocal microscopy, and determination of MBC and MBEC50 values.Transcriptome data suggested that OmpH is a critical gene in the Cec4-mediated removal of CRAB biofilms. While deletion of OmpH did not affect bacterial growth, it reduced capsule thickness, enhanced biofilm formation, and increased the susceptibility of biofilm-embedded A. baumannii to Cec4.Cec4 disrupts CRAB biofilms through targeting OmpH. Loss of OmpH leads to thicker biofilms but simultaneously increases bacterial sensitivity to Cec4, thereby facilitating more effective biofilm removal.
