In vitro activities of tritrpticin alone and in combination with other antimicrobial agents against Pseudomonas aeruginosa

The in vitro activity of the cathelicidin tritrpticin was investigated against multidrug-resistant Pseudomonas aeruginosa. The isolates were susceptible to the peptide at concentrations of 0.50 to 8 mg/liter. Tritrpticin completely inhibits lipopolysaccharide procoagulant activity at a 10 p,M concentration. Fractionary inhibitory concentration indexes (0.385, 0.312, and 0.458) demonstrated synergy between the peptide and beta-lactams.