Lidocaine Gel Interferes With the Antibacterial Activity of Povidone-Iodine

Retina specialists use lidocaine gel as a topical anesthetic. We determined the antibacterial interaction between povidone-iodine (PI) and lidocaine gel using corneoscleral tissue as a solid phase medium.

Five pieces of corneoscleral tissue in five trials were inoculated with 1.000 colony-forming units of bacteria isolated from endophthalmitis. Inoculated corneal tissue were overlaid with nothing (control), lidocaine gel, 5% PI, lidocaine gel over 5% PI, and 5% PI over lidocaine gel for 5 minutes prior to placement in growth liquid medium at 37°C. Growth was monitored for 48 hours.

Application of lidocaine gel prior to 5% PI application provided for the growth of the five bacterial isolates, whereas 5% PI prior to lidocaine gel prevented growth.

Using corneoscleral tissue, PI and lidocaine gel appear to have an antagonistic interaction when lidocaine gel is applied initially prior to 5% PI, preventing bactericidal activity of PI. [.