To Investigate the Antibacterial and Antibiofilm Activity of the Antimicrobial Peptide FP-CATH against Carbapenem-Resistant <i>Klebsiella pneumoniae</i>

In light of the increasing prevalence of carbapenem-resistant <i>Klebsiella pneumoniae</i> (CRKP), which represents a significant public health threat, it is imperative to investigate novel therapeutic strategies. This study aims to assess the efficacy of the novel antimicrobial peptide FP-CATH against CRKP, elucidate its potential mechanism of action, evaluate its safety profile and influencing factors, and determine whether FP-CATH possesses anti-inflammatory properties. A total of 15 CRKP strains (comprising 6 KPC2, 6 NDM-1, and 3 KPC2 + NDM-1) and 8 carbapenem-susceptible <i>K. pneumoniae</i> (CSKP) strains were selected for testing. The broth microdilution method was employed to ascertain the minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) of FP-CATH against these strains. The ability of FP-CATH to disrupt established CRKP biofilms was assessed by using crystal violet staining. The mechanism of action of FP-CATH was investigated by using NPN and PI fluorescent probes. Serum coincubation experiments were conducted to evaluate the serum stability of FP-CATH. Additionally, RT-qPCR was utilized to measure the expression of inflammatory factor genes in bacterially infected cells. Finally, the efficacy of FP-CATH was validated in vivo using a <i>Galleria mellonella</i> infection model.