Antimicrobial Activity of Poly-epsilon-lysine Peptide Hydrogels Against Pseudomonas aeruginosa

Purpose To determine the antimicrobial activity of poly-epsilon-lysine (pɛK) functionalization of hydrogels against Pseudomonas aeruginosa . Methods Antimicrobial activities of pɛK and pɛK+ hydrogels were tested against both keratitis and a laboratory strain of P aeruginosa at a range of inocula sizes, over 4 and 24 hours. The number of viable CFU on pɛK and pɛK+ hydrogels or commercial contact lenses (CL) was investigated. Ex vivo porcine corneas were inoculated with P aeruginosa PAO1 (10 3 CFU) and incubated with pɛK+ hydrogels or commercial hydrogel CL for 24 hours and the effects of infection determined. Results PɛK+ hydrogels showed log reductions in viable CFU compared with pɛK hydrogels for all P aeruginosa strains, depending on inocula sizes and incubation time. After 24 hours pɛK+ hydrogels showed >5 and >7.5 log reduction in CFU compared with commercial hydrogel CL at 10 3 and 10 6 CFU, respectively. In an ex vivo porcine corneal infection model, pɛK+ hydrogels led to a significant decrease in viable PAO1 CFU and histologic analysis indicated a decreased infiltration of PAO1 into the stroma. Conclusions PɛK+ hydrogels demonstrated enhanced antimicrobial activity versus nonfunctionalized pɛK hydrogels against clinically relevant P aeruginosa strains. PɛK+ hydrogels have the potential to be used as a bandage CL with innate antimicrobial characteristics to minimize the risk of microbial keratitis.