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

PURPOSE: To assess the in vitro antimicrobial activity of a new commercial
ophthalmic solution containing povidone-iodine 0.6% (IODIM® ).
METHODS: 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 1 ml and
incubated at 37°C. At different time-points (1, 5, 10, 15, 20, 25, 30 min and
24 hr), 10 μl of each suspension was removed, seeded on Columbia blood agar base
and Sabouraud-dextrose agar plates and then incubated for 24 hr at 37°C. Positive
and negative controls were included in all experiments.
RESULTS: After 5-min incubation, there was no bacterial growth on any plate.
Conversely, IODIM® failed to kill the Candida isolates after 30 min' exposure and
needed 24 hr to eradicate the organisms.
CONCLUSION: 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.