In vitro antibacterial activity of NET1 and NET3 peptide against carbapenem-resistant and susceptible Klebsiella pneumoniae

Purpose: In recent years, antimicrobial resistance is one of the biggest and most important reasons for the difficulties in treating infections and threatening public health. One of the priority pathogens listed by the World Health Organization is carbapenem resistant Enterobacterales (Klebsiella pneumoniae). Antimicrobial peptides are considered as alternatives to antibiotics due to their broad-spectrum antibacterial properties and the difficulty of developing resistance. In this study, we investigated the antimicrobial effects of NET1 and NET3 peptides, which are known to have antimicrobial effects on different bacteria, on carbapenem-resistant and -susceptible K. pneumoniae control strains. Methods: NET1 and NET3 peptides were synthesized and purified. In vitro antibacterial activity of the peptides against carbapenem-resistant and susceptible K. pneumoniae was demonstrated by minimum inhibitory concentration test and minimum bactericidal concentration test. In addition, the mechanism of action of the peptides on carbapenem-resistant K. pneumoniae cells was investigated by scanning electron microscopy. Results: The minimum inhibitory concentration and minimum bactericidal concentration results of NET1 peptide are 4 µg/ml for carbapenem-resistant K. pneumoniae and 2 µg/ml for NET3 peptide. Scanning electron microscope imaging has shown that NET3 peptide exhibits antibacterial activity by damaging the carbapenem-resistant K. pneumoniae cell membrane and disrupting the permeability of the outer membrane. Conclusion: When our results are evaluated, we show that NET1 and NET3 peptide has the potential to be a new generation broad-spectrum antibiotic candidate that can be used for the treatment of carbapenem-resistant K. pneumoniae infection.