PEGylation of Tobramycin Improves Mucus Penetration and Antimicrobial Activity against Pseudomonas aeruginosa Biofilms in Vitro.

Pseudomonas aeruginosa is the predominant pathogen in the persistent lung infections of cystic fibrosis (CF) patients among other diseases. One of the mechanisms of resistance of P. aeruginosa infections is the formation and presence of biofilms. Previously, we demonstrated that PEGylated-tobramycin (Tob-PEG) had superior antimicrobial activity against P. aeruginosa biofilms compared to tobramycin (Tob). The goal of this study was to optimize the method of PEGylation of Tob and assess its activity in an in vitro CF-like mucus barrier biofilm model. Tob was PEGylated using three separate chemical conjugation methods and analyzed by 1H NMR. A comparison of the Tob-PEG products from the different conjugation methods showed significant differences in the reduction of biofilm proliferation after 24 h of treatment. In the CF-like mucus barrier model, Tob-PEG was significantly better than Tob in reducing P. aeruginosa proliferation after only 5 h of treatment ( p < 0.01). Finally, Tob-PEG caused a reduction in the number of surviving P. aeruginosa biofilm colonies higher than that of Tob ( p < 0.0001). We demonstrate the significantly improved antimicrobial activity of Tob-PEG against P. aeruginosa biofilms compared to Tob using two PEGylation methods. Tob-PEG had better in vitro activity compared to that of Tob against P. aeruginosa biofilms growing in a CF-like mucus barrier model.