Ocular Microbiology and Immunology Group
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2019 OMIG Abstract
Novel Ocular Formulations of Elemental Iodine Demonstrate Rapid Antimicrobial Activity against Ocular Bacteria and Yeast

Eric G. Romanowski, MS¹, John E. Romanowski¹, Johannes Korward², Kathleen A. Yates, BS¹,
Hazel Q. Shanks¹, Robert M. Q. Shanks, PhD¹ and Regis P. Kowalski, MS, M(ASCP)^1
1The Charles T. Campbell Ophthalmic Microbiology Laboratory, UPMC Eye Center, University of Pittsburgh School of Medicine, Pittsburgh, PA; ²Novaliq GmbH, Heidelberg, Germany

Methods: Antimicrobial activity against keratitis isolates of methicillin-susceptible and -resistant Staphylococcus aureus (MSSA, MRSA), methicillin-susceptible and -resistant coagulase-negative Staphylococcus (MSCNS, MRCNS), fluoroquinolone-susceptible and -resistant Pseudomonas aeruginosa (FSPA, FRPA), Serratia marcescens (SM), and Candida albicans (CA) was determined using a time-kill assay. Tested microorganisms were individually placed into separate tubes containing 1000, 300, 100 or 0 µg/ml of elemental iodine in the two different EyeSol® vehicles for 1, 2, 5, and 10 minutes. Resulting colony counts were subsequently determined at those time points for iodine and vehicle formulations. Similarly, the microbes were also placed into tubes containing 1000, 300, 100 or 0 µg/ml of povidone-iodine (PI) in PBS and colony counts determined at the same time-points. The Log¹⁰ reduction in colony counts from the iodine or PI containing samples were determined compared to the vehicle controls.

Results: Elemental iodine at 1000 and 300 µg/ml in both the EyeSol® vehicles produced complete kill (106-108 CFU) in 1 minute for all isolates. Elemental iodine at 100 µg/ml in both the EyeSol® vehicles produced complete kill (106-108 CFU) in 1 minute for all isolates except SM and CA. CFU reductions produced for SM were <3 Log10 at all time-points in both EyeSol® vehicles. CFU reductions produced for CA were <3 Log¹⁰ up to 5 minutes but were >3 Log¹⁰ for only one of the EyeSol® vehicles at 10 minutes. PI produced complete kill of all isolates at 1 minute for all concentrations tested.

Conclusion: Elemental iodine, at concentrations of 1000 and 300 µg/ml and contained in two water-free EyeSol® vehicles, demonstrated rapid antimicrobial activity against several Gram-positive and Gram-negative bacterial species and a yeast species. Further development of these novel formulations of elemental iodine are indicated.

Disclosure: S: Campbell Lab (Novaliq GmbH); E: JK

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