Antibacterial activity of anesthetic solutions and preservatives: an in vitro comparative study.
OBJECTIVE
To investigate the antibacterial activity of topical anesthetic solutions and their preservatives individually in vitro, to determine involvement with bacterial growth inhibition.


METHODS
Proparacaine and tetracaine (in concentrations of 0.125%, 0.25%, and 0.50%), edetate disodium (EDTA), benzalkonium chloride, EDTA + benzalkonium chloride, and sterile saline solution were used. Five microliters of each solution were applied to standard filter paper disks and placed in Mueller-Hinton agar previously inoculated with known strains of Pseudomonas aeruginosa and Staphylococcus aureus. Zones of growth inhibition were measured 24 hours later and analyzed.


RESULTS
There were no zones of inhibition in the agar inoculated with P. aeruginosa to all tested solutions. Benzalkonium chloride alone and associated with EDTA inhibited growth of S. aureus. All other solutions did not inhibit S. aureus.


CONCLUSIONS
Preservative-free anesthetic solutions seemed not to interfere with bacterial development in culture media. Benzalkonium chloride alone and associated with EDTA inhibited development of gram positive bacteria, S. aureus, but did not inhibit P. aeruginosa.
Dantas
P E
PE
Department of Ophthalmology and Microbiology/Santa Casa of São Paulo, Brazil. speyecare@originet.com.br
Uesugui
E
E
Nishiwaki-Dantas
M C
MC
Mimica
L J
LJ
D000779:Anesthetics, Local / Q000494:pharmacology*; D000900:Anti-Bacterial Agents / Q000494:pharmacology*; D001548:Benzalkonium Compounds / Q000494:pharmacology*; D008826:Microbial Sensitivity Tests; D009883:Ophthalmic Solutions / Q000494:pharmacology; D011310:Preservatives, Pharmaceutical / Q000494:pharmacology*; D011430:Propoxycaine / Q000494:pharmacology; D011550:Pseudomonas aeruginosa / Q000187:drug effects* / Q000502:physiology; D013211:Staphylococcus aureus / Q000187:drug effects* / Q000502:physiology; D013748:Tetracaine / Q000494:pharmacology
D000779:Anesthetics, Local; D000900:Anti-Bacterial Agents; D001548:Benzalkonium Compounds; D009883:Ophthalmic Solutions; D011310:Preservatives, Pharmaceutical; D013748:Tetracaine; C005717:proxymetacaine; D011430:Propoxycaine