抄録
Benzalkonium chloride is most commonly used as a preservative for ophthalmic solutions at a dosage of 50 μg/mL. In this study, we evaluated the antibacterial activity of this preservative against 16 species and64 clinically isolated strains. Benzalkonium chloride demonstrated a good effect on gram-positive cocci, the minimum inhibitory concentrations (MICs) of benzalkonium chloride to Staphylococcus epidermidis and Staphylococcus aureus including MRSA were less than 12.5μg/mL. On the other hand, benzalkonium chloride was not effective against gram-negative rods ; 95% (42/44) of gram-negative rods strains were not susceptible after treatment with 50μg/mL of benzalkonium chloride. Especially, the MICs of benzalkonium chloride to clinically isolated pseudomonas aeruginosa were over 200μg/mL. These results suggest that benzalkonium chloride as preservative for ophthalmic solutions in effective on gram-positive cocci even when used in concentrationsonly one fourth times as much as those commercially available and to gram-negative rods when used in concentrations which may cause damage to the comeas. The use of lower concentration of benzalkonium chloride may therefore make it possible to reduce the degree of damage to the cellular components of the cornea.
