Effective antimicrobial activity of Cbf-14-2 against penicillin-resistant bacteria in vitro and in vivo

The antibacterial activity and mechanism of the antimicrobial peptide mutant Cbf-14-2 against NDM-1 carrying recombinant bacteria(E. coli BL21(DE3)-NDM-1)was investigated in this study. The minimum inhibitory concentration(MIC), minimum bactericidal concentration(MBC)and killing curves(KCs) in vitro were determined by the broth microdilution method. Mice septicemia model was established by interaperitotoneal injection of E. coli BL21(DE3)-NDM-1 to evaluate the antibacterial activity of this peptide in vivo. Results showed that Cbf-14-2 exhibited a potent antibacterial activity with MIC of 16 μg/mL and killed almost all recombinant bacteria within 120 min. Meanwhile, it significantly improved the survival rate of infected mice up to 70% with the decreasing of bacterial load in mice lung, liver, spleen and kidney. This powerful clearance ability of Cbf-14-2 against bacteria mainly related to its enhanced membrane penetration ability through neutralizing the negative charges and disrupting the integrity of the bacterial cell membrane. Therefore, Cbf-14-2 is expected to be a potential antimicrobial agent for the treatment of infection induced by multi-drug resistant bacteria, especially for the NDM-1carrying bacteria.