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Published on: September 20, 2024
Efficacy of commercial soft contact lens disinfectant solutions against Acanthamoeba
Takeshi Kobayashi1, Lindsay Gibbon2, Tsuyoshi Mito2
1Department of Ophthalmology and Regenerative Medicine, Ehime University Graduate School of Medicine, Shitsukawa, Toon, Ehime, 791-0295, Japan.
Purpose:
To investigate the relative efficacy of Japanese commercial soft contact lens disinfectant solutions against Acanthamoeba trophozoites and cysts.
Materials And Methods:
Eight types of multipurpose solution (MPS), two types of hydrogen peroxide solution, and one povidone-iodine solution were evaluated to determine their effect against Acanthamoeba trophozoites and cysts (ATCC 50514). Acanthamoeba cysts were cultured in encystment medium for either 1 or 2 weeks (1 and 2-week-old cysts). The trophozoites and cysts were treated with each disinfectant solution for 0, 2, 4, 8, or 24 h. After performing four tenfold serial dilutions of each test solution, dilutions were cultured for 10 days. The number of surviving organisms was calculated using the trimmed Spearman-Karber method.
Results:
Among the MPS tested, only four were effective against trophozoites after treatment for 4 h, and none was effective against 2-week-old cysts. Hydrogen peroxide had a significant effect on trophozoites and 1-week-old cysts, but not on 2-week-old cysts. In contrast, povidone-iodine caused a 2.6 log reduction in 2-week-old cysts.
Conclusions:
MPS were found to have limited efficacy against trophozoites and no efficacy against 2-week-old cysts. Only povidone-iodine had any efficacy against 2-week-old cysts.
Insights
Multipurpose solutions show limited effectiveness against Acanthamoeba, especially mature cysts. Povidone-iodine offers some efficacy against Acanthamoeba cysts, but contact lens disinfectants require further development.
Area of Science:
- Ophthalmology
- Microbiology
- Infectious Diseases
Background:
- Acanthamoeba keratitis is a severe eye infection.
- Contact lens disinfectants are crucial for preventing microbial contamination.
- The efficacy of commercial disinfectants against Acanthamoeba, particularly in its cyst stage, needs thorough evaluation.
Purpose of the Study:
- To compare the efficacy of Japanese commercial soft contact lens disinfectant solutions against Acanthamoeba trophozoites and cysts.
- To assess the effectiveness of multipurpose solutions (MPS), hydrogen peroxide, and povidone-iodine against different life stages of Acanthamoeba.
Main Methods:
- Eight MPS, two hydrogen peroxide solutions, and one povidone-iodine solution were tested.
- Acanthamoeba trophozoites and cysts (1- and 2-week-old) were exposed to disinfectants for varying durations (0-24 hours).
- Organism viability was determined by serial dilution and culturing, analyzed using the trimmed Spearman-Karber method.
Main Results:
- Four MPS demonstrated efficacy against trophozoites within 4 hours, but none were effective against 2-week-old cysts.
- Hydrogen peroxide was effective against trophozoites and 1-week-old cysts, but not 2-week-old cysts.
- Povidone-iodine achieved a 2.6 log reduction in 2-week-old cysts.
Conclusions:
- Multipurpose solutions exhibit limited efficacy against Acanthamoeba trophozoites and no efficacy against mature cysts.
- Hydrogen peroxide solutions are not effective against 2-week-old Acanthamoeba cysts.
- Povidone-iodine is the only tested disinfectant showing some efficacy against mature Acanthamoeba cysts.
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