In vitro antimicrobial activity of a new ophthalmic solution containing povidone-iodine 0.6% (IODIM® ).

Abstract

To assess the in vitro antimicrobial activity of a new commercial ophthalmic solution containing povidone-iodine 0.6% (IODIM® ). Staphylococcus aureus ATCC 43300, Pseudomonas aeruginosa ATCC 27853, three ocular bacterial isolates (1 S.epidermidis, 1 S.aureus, 1 P.aeruginosa) and five Candida species were used. The bacterial and fungal isolates were cultured on Columbia blood agar base plates and Sabouraud-dextrose agar plates, respectively and incubated overnight at 37°C. Bacterial and fungal suspensions in sterile saline solution were prepared to an optical density equal to 0.5 McFarland standard (approximately 108 CFU/ml). Suspensions of the isolates were made in IODIM® solution to obtain a final concentration of 106 CFU/ml. The suspensions were then distributed in conical tubes in a final volume of 1ml and incubated at 37°C. At different time-points (1, 5, 10, 15, 20, 25, 30min and 24hr), 10μl of each suspension was removed, seeded on Columbia blood agar base and Sabouraud-dextrose agar plates and then incubated for 24hr at 37°C. Positive and negative controls were included in all experiments. After 5-min incubation, there was no bacterial growth on any plate. Conversely, IODIM® failed to kill the Candida isolates after 30min' exposure and needed 24hr to eradicate the organisms. IODIM® ophthalmic solution showed in vitro antimicrobial activity against S.epidermidis, S.aureus, P.aeruginosa and Candida species. Results suggest that it may be a potential candidate for the treatment of ocular surface infections and antimicrobial prophylaxis before intravitreal injections.