Cephalosporin nitric oxide-donor prodrug DEA-C3D disperses biofilms formed by clinical cystic fibrosis isolates of Pseudomonas aeruginosa

Objectives: The cephalosporin nitric oxide (NO)-donor prodrug DEA-C3D (DiEthylAmin-Cephalosporin-3’- Diazeniumdiolate) has been showed to initiate the dispersal of biofilms formed by Pseudomonas aeruginosa laboratory strain PAO1. In this study, we investigated whether DEA-C3D disperses biofilms formed by clinical cystic fibrosis isolates of P. aeruginosa and its effect in combination with two anti-pseudomonal antibiotics, tobramycin and colistin, in vitro.

Methods: -lactamase-triggered release of NO from DEA-C3D was confirmed using a gas-phase chemiluminescence detector. MICs against P. aeruginosa clinical isolates were measured using the broth microdilution method. A crystal violet staining technique and confocal laser scanning microscopy were used to evaluate the effects of DEA-C3D on P. aeruginosa biofilms alone and in combination with tobramycin and colistin.

Results: DEA-C3D was confirmed to selectively release NO in response to contact with bacterial -lactamase. Despite lacking direct, cephalosporin/-lactam-based antibacterial activity, DEA-C3D was able to disperse biofilms formed by three P. aeruginosa clinical isolates. Confocal microscopy revealed that DEA-C3D in combination with tobramycin produces similar reductions in biofilm to DEA-C3D alone, whereas the combination with colistin causes near complete eradication of P. aeruginosa biofilms in vitro.

Conclusions: DEA-C3D is effective in dispersing biofilms formed by multiple clinical isolates of P. aeruginosa and could hold promise as a new adjunctive therapy to patients with CF.