Corneal storage medium preservation with defensins.

We used a synthetic defensin (rabbit neutrophil peptide-1; NP-1) as a microbicide in a corneal storage medium, Optisol without antimicrobial compounds. We established growth curves in Optisol for Staphylococcus aureus, Streptococcus pneumoniae, and Pseudomonas aeruginosa. Each organism was evaluated separately at 4 degrees C, 23 degrees C, and 37 degrees C in Optisol with NP-1 at each of four different concentrations including 1, 10, 100, and 200 micrograms/ml. When the three organisms were evaluated in Optisol containing NP-1, we found that a concentration of 200 micrograms/ml of NP-1 successfully killed 99.9% (the limits of our assay) of all three organisms at all temperatures tested. We conclude that NP-1 exhibits promise as a nonantibiotic preservative agent in corneal storage media, since it was effective in killing organisms at all temperatures, including 4 degrees C.