The study shows that synthetic antimicrobial compounds called ceragenins kill bacteria and fungi in cystic fibrosis lung fluid even when salt levels are high, while the natural peptide LL‑37 loses much of its killing power under the same salty conditions.

The purpose of the work was to investigate the impact of sodium chloride (NaCl) on the antimicrobial efficacy of ceragenins (CSAs) and antimicrobial peptides (AMPs) against bacterial and fungal pathogens associated with cystic fibrosis (<i>CF</i>) lung infections. <i>CF</i>-associated bacterial (<i>Pseudomonas aeruginosa</i>, <i>Ochrobactrum</i> spp., and <i>Staphylococcus aureus</i>), and fungal pathogens (<i>Candida albicans</i>, and <i>Candida tropicalis</i>) were used as target organisms for ceragenins (CSA-13 and CSA-131) and AMPs (LL-37 and omiganan). Susceptibility to the tested compounds was assessed using minimal inhibitory concentrations (MICs) and bactericidal concentrations (MBCs), as well as by colony counting assays in <i>CF</i> sputum samples supplemented with various concentrations of NaCl. Our results demonstrated that ceragenins exhibit potent antimicrobial activity in <i>CF</i> sputum regardless of the NaCl concentration when compared to LL-37 and omiganan. Given the broad-spectrum antimicrobial activity of ceragenins in the microenvironments mimicking the airways of <i>CF</i> patients, ceragenins might be promising agents in managing <i>CF</i> disease.