Bactericidal activity of ceragenin CSA-13, CSA-44 and CSA-131 against bacteria causing bloodstream infections

Angelika Mańkowska¹Paulina Paprocka¹Łukasz Suprewicz²Agata Lesiak¹Kamila Fortunka¹Grzegorz Król¹Jakub Spałek¹Sławomir Okła¹Bonita Durnaś¹Tamara Daniluk³Ewelina Piktel³Paul B. Savage⁴Robert Bucki^1,3*

• ¹Department of Microbiology and Immunology, Institute of Medical Science, Collegium Medicum, Jan Kochanowski University in Kielce, Kielce, Poland
• ²Department of Medical Microbiology and Nanobiomedical Engineering, Medical University of Białystok,, Białystok, Poland
• ³Department of Medical Microbiology and Nanobiomedical Engineering, Medical University of Białystok, Białystok, Poland
• ⁴Department of Chemistry and Biochemistry, Brigham Young University, Provo, United States

The constantly growing resistance of bacteria causing bloodstream infections and the lack of alternative antibiotics generate the need to develop new therapeutic strategies. In this study, the antibacterial properties of synthetic cholic acid derivatives ceragenins CSA-13, CSA-44 and CSA-131, custom-synthesized peptides human cathelicidin LL-37 peptide, synthetic WLBU2 peptide, and antimicrobial VFR12 peptide of human thrombin origin were determined by measuring minimum inhibitory concentrations/minimum bactericidal concentrations (MIC/MBC) against clinical bacterial strains and compared with activity of clinically used antibiotics colistin and vancomycin. The therapeutic potentials of the tested agents were assessed in the presence of 50% blood plasma and their hemolytic properties were determined using human red blood cells (RCB). Additionally, the antimicrobial activity of CSA-13 against selected clinical strains was assessed using a killing assay. Plasma cytokine levels were determined and endothelial cell confluent monolayer permeability was assessed using the FITC-dextran and measurement of transepithelial electrical resistance (TEER). The obtained data show that under experimental conditions mimicking blood environment, ceragenins display higher antimicrobial activity compared to the cationic peptides regardless of the bacterial species. The presence of blood plasma slightly decreases the effect of ceragenins, but does not significantly affect their antibacterial properties or their hemolytic activity, especially in case of ceragenin CSA-13. Furthermore, CSAs at bactericidal concentrations do not induce hemolysis of red blood cells. CSA-13 dose-dependently regulates the permeability of human umbilical vein endothelial cells (HUVECs) monolayers as well as affects the secretion of cytokines, which may indicate its ability to modulate immune responses. The obtained data confirm the antibacterial activity of ceragenins against clinical strains of bacteria isolated from blood, their influence on the immune system and the integrity of the endothelial cell monolayer, but further studies are necessary to understand the cell signaling pathway governing these effects.