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

Figures & data

Figure 1 Diagram detailing the experimental steps for the elimination of bacteria attached to corneoscleral tissue by topical antiseptics.

Table 1 Comparison of 5% and 2.5% Povidone Iodine Antibacterial Efficacy to 0.01% Hypochlorous Acid Using Bacteria Isolated from Endophthalmitis. Corneoscleral Tissue Was Used as a Solid-Phase Medium to Assimilate the Ocular Surface. Prevention of Bacterial Growth After Antiseptic Application Indicated Success of the Antiseptic

Bacteria	Untreated	5% Povidone Iodine	2.5% Povidone Iodine	0.01% Hypo-Chlorous Acid	Isolates 1993–2019	Percent Incidence 1993–2019	# Per Year
Coag Negative Staph E877	POS	Neg	Neg	POS	424	61.5%	15.7
Coag Negative Staph E923	POS	Neg	Neg	POS	–	–	–
Coag Negative Staph E922	POS	Neg	Neg	Neg	–	–	–
Coag Negative Staph E920	POS	Neg	Neg	POS	–	–	–
Staphylococcus aureus E904	POS	Neg	Neg	Neg	80	11.6%	2.96
Streptococcus viridans E927	POS	Neg	POS	Neg	61	8.8%	2.26
Streptococcus viridans E926	POS	POS	POS	POS	–	–	–
Streptococcus viridans E919	POS	Neg	POS	POS	–	–	–
Streptococcus viridans E910	POS	Neg	Neg	POS	–	–	–
MRSA E897	POS	Neg	Neg	NEG	29	4.2%	1.07
Streptococcus pneumoniae E891	POS	Neg	Neg	POS	26	3.8%	0.96
Streptococcus pneumoniae E845	POS	Neg	Neg	POS	–	–	–
Streptococcus pneumoniae E737	POS	Neg	Neg	Neg	–	–	–
Streptococcus pneumoniae E709	POS	Neg	Neg	POS	–	–	–
Beta hemolytic Streptococcus E819	POS	POS	POS	POS	15	2.2%	0.55
Enterococcus faecalis E913	POS	POS	POS	POS	14	2.0%	0.52
Bacillus cereus E776	POS	POS	POS	POS	14	2.0%	0.52
Serratia marcescens E886	POS	NEG	neg	POS	10	1.4%	0.37
Pseudomonas aeruginosa E915	POS	Neg	Neg	POS	9	1.3%	0.33
Haemophilus influenzae E789	POS	Neg	Neg	POS	7	1.0%	0.26
Percent Positive	20 of 20,100%	4 of 20 20%	6 of 20 30%	15 of 20 75%	–		–

Notes: Bacteria – These were representative bacteria isolated from endophthalmitis for this study. Other bacterial genus and species were isolated, but not tested. The E followed by a number indicates the endophthalmitis isolate number from the clinical bank collection. “POS” indicates positive-growth in liquid medium and treatment failure. “neg” indicates no growth in liquid medium, and treatment success. 5% povidone iodine was equally effective to 2.5% povidone iodine for preventing bacteria growth (χ², p=0.71). Both 5% (χ², p=0.0005) and 2.5% (χ², p=0.004) povidone iodine were more effective for eliminating bacteria than 0.01% hypochlorous acid.

Table 2 Weighted Comparison of 5% and 2.5% Povidone Iodine Antibacterial Activity to 0.01% Hypochlorous Acid Based on Bacteria Isolated from Endophthalmitis Over a 27-Year Period (1993–2019). Corneoscleral Tissue Was Used as a Solid-Phase Medium to Assimilate the Ocular Surface. Prevention of Bacterial Growth After Antiseptic Application Indicated Success of the Antiseptic

Bacteria	Isolates (1993–2019)	No Antiseptic	5% Povidone Iodine	2.5% Povidone Iodine	0.01% Hypochlorous Acid
Coagulase Negative Staphylococcus*	424	424	0	0	318 (0.75 of 424)
Staphylococcus aureus	80	80	0	0	0
Streptococcus viridans*	61	61	15 (0.25 of 61)	46 (0.75 of 61)	46 (0.75 of 61)
Methicillin- Resistant Staphylococcus aureus	29	29	0	0	0
Streptococcus pneumoniae*	26	26	0	0	20 (0.75 of 26)
Beta hemolytic Streptococcus	15	15	15	15	15
Enterococcus	14	14	14	14	14
Bacillus	14	14	14	14	14
Serratia marcescens	10	10	0	0	10
Pseudomonas aeruginosa	9	9	0	0	9
Haemophilus influenzae	7	7	0	0	7
Percent Positive	689	100% (689 of 689)	8.4% (58 of 689)	13.0% (89 of 689)	66% (453 of 689)

Notes: Asterisk indicates that 4 representative isolates each were tested for growth by coagulase negative Staphylococcus, Streptococcus viridans, and Streptococcus pneumoniae. Parenthesis indicates the estimated percent positive of total number of isolates in the 27-year period 1993–2019 based on the testing of the 4 isolates from Table 1. For all bacterial groups except Streptococcus viridans, 5% povidone iodine was equally effective to 2.5% povidone iodine for preventing bacteria (χ2, p=1.0). For Streptococcus viridans, 5% povidone iodine was more effective than 2.5% povidone iodine for reducing growth (χ², p=0.0001). Both 5% (χ2, p=0.00001) and 2.5% povidone iodine (χ2, p=0.00001) were more effective than 0.01% hypochlorous acid.