Polyhexanide, Povidone-Iodine, and Hypochlorous Acid Show High In Vitro Antimicrobial Efficacy Against Pathogens...

Area of Science:

• Veterinary Ophthalmology
• Antimicrobial Research
• Equine Infectious Diseases

Background:

• Equine ulcerative keratitis is frequently caused by bacterial pathogens.
• Effective antimicrobial treatment is crucial for preserving vision in horses.
• Identifying potent antiseptics is key to managing ocular infections.

Purpose of the Study:

• To evaluate the in vitro antimicrobial activity of specific antiseptics against common equine ocular surface pathogens.
• To determine the minimum bactericidal concentrations (MBC) of polyhexanide, povidone-iodine, and hypochlorous acid.
• To compare the efficacy of these antiseptics against various bacterial isolates from horses.

Main Methods:

• Bacterial isolates including Staphylococcus aureus, Streptococcus equi subspecies zooepidemicus, Enterobacter hormaechei, and Bacillus cereus were obtained from horses with ulcerative keratitis.
• Minimum bactericidal concentrations (MBC) were determined using the microdilution method.
• Subculturing and colony counting followed Clinical and Laboratory Standards Institute guidelines.

Main Results:

• Polyhexanide demonstrated MBC values ranging from 0.8 to 6.4 ppm.
• Povidone-iodine showed MBC values between 4 and 32 ppm.
• Hypochlorous acid exhibited MBC values from 0.4 to 6.4 ppm, with effectiveness comparable to other tested agents against both methicillin-resistant and susceptible Staphylococcus aureus.

Conclusions:

• All tested antiseptics exhibited high in vitro efficacy against common equine ocular bacterial pathogens at concentrations below those in commercial products.
• These findings suggest potential applications for these antiseptics in treating equine infectious ocular surface diseases, possibly as alternatives or adjuncts to topical antibiotics.
• Further in vivo and clinical studies are warranted to confirm the translatability of these in vitro results to clinical settings.