In vitro activity of ceragenins against Burkholderia cepacia complex

Burkholderia cepacia complex (Bcc) species are aerobic, Gram-negative and non-fermantative bacilli. Bcc can cause clinical symptoms in patients with cystic fibrosis, ranging from asymptomatic carriage to fatal pneumonia. A pressing need exists for new antimicrobial agents that target Bcc. Ceragenins, CSA-13, CSA-131 and CSA-131 with 5% Pluronic® F127 (CSA-131P), were evaluated against Bcc clinical isolates (n = 42). MICs of ceragenins and conventional antibiotics were determined. Time-kill curve experiments were performed with 1x, 4x MICs of ceragenins and sulfamethoxazole-trimethoprim (SXT), levofloxacin. MIC₅₀/ MIC₉₀ results (mg l^-1) of CSA-13, CSA-131 and CSA-131P were determined as 16/64, 16/128 and 16/128, respectively. CSA-13 and CSA-131 showed bactericidal activity. CSA-13 - levofloxacin combination displayed synergistic activity against Bcc. First-generation (CSA-13) and second-generation (CSA-131 and CSA-131P) ceragenins have significant antimicrobial effects on Bcc. The findings of this study demonstrate that combinations of ceragenins with currently marketed antibiotics could be synergistic in vitro against Bcc isolates. These results suggest that combination therapy with conventional antibiotics could be an alternative approach for treating Bcc infections in the future.