The Antibacterial Comparison of 5% and 2.5% Povidone Iodine to 0.01% Hypochlorous Acid Using Corneoscleral Tissue as a Solid-Phase Medium

Regis Kowalski,1 Roheena Kamyar,1 Michelle Rhee,2 Alex Mammen,1 Deepinder Dhaliwal,1 Eric G Romanowski,1 Vishal Jhanji,1 Andrew W Eller1 1University of Pittsburgh Medical Center (UPMC), The Charles T. Campbell Ophthalmic Microbiology Laboratory, Department of Ophthalmology, University of Pittsburgh School of Medicine, Pittsburgh, PA, USA; 2The Eye-Bank for Sight Restoration, New York, NY, USACorrespondence: Regis KowalskiThe Charles T. Campbell Ophthalmic Microbiology Laboratory at the University of Pittsburgh School of Medicine, The Eye and Ear Institute, 203 Lothrop Street, Pittsburgh, Pa, 15213, USATel +1 412-647-7211Email kowalskirp@upmc.eduPurpose: Prophylactic topical antiseptics used to eliminate bacteria on the ocular surface prior to ocular surgery should be both effective and non-irritating. Five percent povidone iodine (PI) is an accepted antiseptic used for prophylaxis. Dilute 2.5% PI and 0.01% hypochlorous acid (HOCl) may be more patient comfortable and equally effective. PI at 5% and 2.5% were compared to HOCl against a battery of bacterial endophthalmitis isolates using corneoscleral tissue as a solid-phase medium to determine antiseptic efficacy.Methods: Bacteria from 20 cases of endophthalmitis were tested for the elimination of growth against topical 5% PI, 2.5% PI, HOCl, and no antiseptic using donor corneoscleral tissue. The tissue was inoculated with 103 colony forming units of bacteria prior to a 3-minute contact time with the antiseptics, placed in liquid growth medium, and monitored for growth at three days. No growth indicated antiseptic treatment success. Differences were analyzed using Chi square (χ 2).Results: For 20 isolates, 5% PI was comparable to 2.5% PI for preventing bacteria growth (p=0.71), and both were more effective than HOCl (p=0.004). Estimated weighted comparison over a 27-year period indicated that for all bacterial groups, except Streptococcus viridans, 5% PI was equally effective to 2.5% PI for preventing bacterial growth (p=1.0). For Streptococcus viridans, 5% PI was more effective than 2.5% PI (p=0.0001). Both concentrations of PI were more effective than HOCl (p=0.00001).Conclusion: Five percent PI appears to be optimal as a prophylaxis prior to ocular surgery.Keywords: povidone iodine, hypochlorous acid, endophthalmitis prophylaxis, intravitreal injection, corneoscleral tissue, antiseptic susceptibilit