Antibacterial Activity of cLFchimera and its Synergistic Potential with Antibiotics against Some Foodborne Pathogens Bacteria

Background: Frequent and unlimited use of antibiotics caused the development of antibiotic resistance by microorganisms. Therefore, there is an argent need to discover novel antibacterial agents or a combination of agents as a safe treatment strategy for various infections. The aim of the present study was to evaluate the synergistic effects of cLFchimera, an antimicrobial peptides (AMPs), and antibiotics on several foodborne bacterial strains. Methods: : A checkerboard method was used to determine the synergistic effects of cLFchimera and several antibiotics (Gentamicin, Cefazolin and Ceftazidime) on bacterial strains ( Escherichia coli , Pseudomonas aeruginosa and Salmonella typhi ). Results: : The combination of cLFchimera and antibiotics generated a total and partial synergistic interaction for all foodborne bacterial strain used in the present study (FIC= 0.25 to 0.77). In most cases, the effect of peptide and antibiotic synergist on release of cellular content was not different compared to antibiotics when they used alone, but the count of viable cells significantly decreased in combination peptide and antibiotics treatments. Generally, antibacterial dynamics of the combination of peptide and antibiotics showed an increase and stable trend after reaching the peak point for E. coli, P. aeruginosa and S. typhi, respectively. Scanning electron microscopy analysis showed that bacterial cells treated with the combination Gentamycin and cLFchimera were markedly damaged, and most of the outermost layer of the bacterial cells disappeared. Conclusion: Overall, our results may suggest that cLFchimera mediated its synergistic activity independent to antibiotics mode of action by disrupting the cell membrane and intramolecular mechanisms.