Antimicrobial activity of a peptide mimic against Pseudomonas aeruginosa in solution and when immobilised onto contact lenses.

Abstract

Purpose : The purpose of this study was to evaluate the antimicrobial activity of peptide mimic 758 against a drug-resistant and biofilm-producing strain of Pseudomonas aeruginosa in solution and when surface immobilised onto contact lenses.

Methods : Minimal inhibitory concentration (MIC) and Minimum bactericidal concentration (MBC) of 758 was measured against the P. aeruginosa strain 6294. 758 was covalently attached to etafilcon A contact lenses via EDC (1-ethyl-3-[3-dimethylaminopropyl] carbodiimide hydrochloride) and NHS (N-hydroxysuccinimide) coupling. High salt (10% NaCl) treatment was carried out to extract any adsorbed peptide to ensure that the activity was only due to 758 peptide mimic attached to the lens surface. The antimicrobial activity of 758 was evaluated against P. aeruginosa by measuring the amount of cell death compared to control uncoated lenses.

Results : MIC and MBC of 758 against P. aeruginosa was 45.5 µg ml^-1 and 91 µg ml^-1 respectively. When allowed to adhere to contact lenses coated with 1mg ml^-1 758 P. aeruginosa adhered to 0.15 log₁₀ colony forming units (cfu/lens) whereas P. aeruginosa adhered to control lenses to ≥ 3. log₁₀ cfu/lens. Therefore, covalently attached 758 was active against drug-resistant and biofilm-producing strain of P. aeruginosa, giving ≥ 2.9 log₁₀ reduction in bacterial counts compared to control lenses.

Conclusions : The peptide mimic 758 showed excellent antimicrobial activity against P. aeruginosa. Future research will examine the activity of 758 against drug-resistant Gram-positive bacteria, to see the potential for development as a broad-spectrum antimicrobial coating for contact lenses.

This is a 2021 ARVO Annual Meeting abstract.