Related Experiment Videos
The effect of currently available contact lens disinfection systems on Acanthamoeba castellanii and Acanthamoeba
R E Silvany1, J M Dougherty, J P McCulley
1Department of Ophthalmology, University of Texas Southwestern Medical Center, Dallas.
Abstract:
Contact lens disinfection systems were evaluated for their effectiveness in killing Acanthamoeba castellanii and Acanthamoeba polyphaga trophozoites and cysts. Amoebae were inoculated into commercially available contact lens cleaning and soaking solutions. At intervals varying from 30 minutes to 24 hours, solutions were filtered. The filters were removed and cultured for Acanthamoeba organisms. Striking differences were observed in the abilities of the different disinfecting solutions to kill the organisms. Solutions containing chlorhexidine were effective at very short exposure times. Solutions containing benzalkonium chloride required slightly longer exposure times but were faster than solutions containing only thimerosal. Solutions containing sorbate, polyaminopropyl biguanide, or polyquaternium-1 were not effective at killing Acanthamoeba organisms in the time allotted for the experiment. Solutions containing hydrogen peroxide were quite effective if the agent was not prematurely catalyzed. A. polyphaga generally required longer exposure to disinfectants than did A. castellanii for complete inhibition to occur.
Insights
Different contact lens disinfectants show varying effectiveness against Acanthamoeba. Chlorhexidine and hydrogen peroxide (uncatalyzed) were most effective, while others like thimerosal and benzalkonium chloride showed moderate results for contact lens disinfection.
Area of Science:
- Ophthalmology
- Microbiology
- Biotechnology
Background:
- Contact lens wear is associated with a risk of microbial keratitis.
- Acanthamoeba keratitis is a severe infection that can lead to vision loss.
- Effective disinfection of contact lenses is crucial for preventing Acanthamoeba infections.
Purpose of the Study:
- To evaluate the efficacy of various commercially available contact lens disinfection systems against Acanthamoeba castellanii and Acanthamoeba polyphaga.
- To compare the killing activity of different disinfectant agents and exposure times.
Main Methods:
- Amoebae (trophozoites and cysts) were inoculated into contact lens cleaning and soaking solutions.
- Solutions were filtered at timed intervals (30 minutes to 24 hours).
- Filters were cultured to assess Acanthamoeba viability and determine disinfectant effectiveness.
Main Results:
- Significant differences in killing efficacy were observed among disinfectants.
- Chlorhexidine-containing solutions demonstrated rapid Acanthamoeba killing.
- Benzalkonium chloride was effective but required longer exposure than chlorhexidine.
- Thimerosal showed slower efficacy compared to chlorhexidine and benzalkonium chloride.
- Sorbate, polyaminopropyl biguanide, and polyquaternium-1 based solutions were ineffective within the experimental timeframe.
- Hydrogen peroxide was effective when not prematurely catalyzed.
- Acanthamoeba polyphaga generally required longer disinfection times than Acanthamoeba castellanii.
Conclusions:
- Disinfectant composition and exposure time are critical factors in eliminating Acanthamoeba from contact lenses.
- Chlorhexidine and uncatalyzed hydrogen peroxide show the most promise for Acanthamoeba disinfection.
- Some common contact lens disinfectants are not sufficiently effective against Acanthamoeba, highlighting the need for careful product selection.