Resistance to a polyquaternium-1 lens care solution and isoelectric points of Pseudomonas aeruginosa strains

• Published in: Journal of antimicrobial chemotherapy 2006-04, Vol.57 (4), p.764-766
• Main Authors: Bruinsma, Gerda M., Rustema-Abbing, Minie, van der Mei, Henny C., Lakkis, Carol, Busscher, Henk J.
• Format: Article
• Language: English
• Subjects: Antibiotics. Antiinfectious agents. Antiparasitic agents; Biological and medical sciences; cationic molecules; Contact Lens Solutions - chemistry; Contact Lens Solutions - pharmacology; Contact Lenses - microbiology; Drug Resistance, Bacterial; Eye - microbiology; Eye Infections - microbiology; Humans; Hydrophobic and Hydrophilic Interactions; hydrophobicity; Isoelectric Point; Medical sciences; Pharmacology. Drug treatments; Polymers - pharmacology; Pseudomonas aeruginosa; Pseudomonas aeruginosa - classification; Pseudomonas aeruginosa - drug effects; Pseudomonas aeruginosa - isolation & purification; Pseudomonas Infections - microbiology; quaternary ammonium compounds; Quaternary Ammonium Compounds - pharmacology; surface charge; Surface Properties
• ISSN: 0305-7453; 1460-2091
• DOI: 10.1093/jac/dkl011

Objectives: The aim of this study was to correlate the cell surface hydrophobicity and charge of various strains of Pseudomonas aeruginosa with their resistance to a polyquaternium-1 lens care solution. Methods: The 11 P. aeruginosa strains included were isolated from eyes, contact lenses, lens cases and lens care solutions. Cell surface hydrophobicities were determined from water contact angle measurements and surface charges were measured as a function of pH using particulate micro-electrophoresis. Results: Strains resistant to polyquaternium-1 had an isoelectric point (IEP; pH where the bacterial zeta potential is zero) ranging from 4.0 to 5.5, whereas susceptible strains were more negatively charged than resistant strains and had an IEP between 1.3 and 1.9. Water contact angles ranged from hydrophilic (34°) to hydrophobic (124°), without showing a relation with antimicrobial resistance. Conclusions: Results suggest that electrostatic repulsion between cationic molecules on the cell surface and quaternary ammonium compounds impedes the antimicrobial entering the cell.