In vitro activities of the novel ceragenin CSA-13, alone or in combination with colistin and other antibiotics against Pseudomonas aeruginosa strains isolated from cystic fibrosis patients

Background Cystic fibrosis (CF) is an autosomal-recessive, life-shortening disease caused by a defect in the CF transmembrane conductance regulator (CFTR) gene encoding the CFTR chloride channel protein. The physiopathologic changes in the lungs of these patients triggers the development of pulmonary infections caused by various microorganisms, most commonly by Pseudomonas aeruginosa, and 80 % of patients become chronically infected with P. aeruginosa over their life times. As chronic infections are difficult to treat, attempts have been made to discover new antimicrobial agents targeting novel sites that may circumvent resistance. Recently, a series of cationic derivatives of cholic acid have been synthesized and have been found to have properties that may make them useful antimicrobial agents. The ceragenins, designed to mimic the activities of antimicrobial peptides, are a new class of antimicrobial agent. Among them CSA-13, a cationic steroid molecule, mimics the activity of naturally occuring antimicrobial peptides.