Studies on the Antibacterial Activity and Mechanism of Antimicrobial Peptides Against Drug-Resistant Bacteria

Antibiotic resistance is a growing threat to human health. More than anything else, multidrug-resistant gram-negative bacteria pose the biggest challenge to healthcare, which is predominantly due to the lack of effective therapeutic options. In the present study, we investigated the activities of peptides HX-12A, HX-12B and HX-12C against MDRAB and MDRKP isolates in vitro. Those three peptides displayed high antibacterial activities and rapid bactericidal effects against MDRAB and MDRKP isolates. Additionally, the peptides retained their activity even being present in pH 6.8 and 8.0, salt (NaCl 100 mM, CaCl2 1 mM, MgCl2 1 mM) or human serum (5%), especially peptide HX-12C. Moreover, the killing kinetics and transmission electron microscopy results suggested that the possible sterilization mechanism of peptides is to destroy the cell membrane, which makes it more difficult for bacteria to develop resistance. Thus, these three peptides may be developed into new antimicrobial agents.