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Published on: September 20, 2024
Efficacy of contact lens systems against recent clinical and tap water Acanthamoeba isolates
Megan E Shoff1, Charlotte E Joslin, Elmer Y Tu
1Department of Evolution, Ecology, and Organismal Biology, The Ohio State University, Columbus, OH 43210, USA. shoff.4@osu.edu
Purpose:
A recent increase in Acanthamoeba keratitis (AK) cases has been associated with Complete MoisturePlus, although many cases used other solutions. Complete MoisturePlus contains taurine and hydroxypropyl methylcellulose, unlike other multipurpose solutions (MPSs). The purpose of this study is to (1) determine contact lens solution efficacy against recent clinical and tap water Acanthamoeba isolates and (2) determine whether taurine inclusion increases Acanthamoeba survival against contact lens solutions.
Methods:
Acanthamoeba T4 trophozoites from recent AK clinical and tap water isolates were placed on multiple concentrations of taurine-saline agar for 72 hours with Enterobacter aerogenes as prey. Amoebae were exposed for 6 and 24 hours to hydrogen peroxide solutions and MPSs (ReNu Multiplus, Complete MoisturePlus, AMO Trade Name, Opti-free Express, Clear Care, and UltraCare) and tested for survival. Plates were examined over the following week for growth.
Results:
Strain type and solution affected survival. MPSs were ineffective, with 100% survival of all strains at 6-hour exposure. Hydrogen peroxide systems were more effective, with survival of 3/5 strains (Clear Care) and 1/5 strains (UltraCare) at 6 hours. The Chicago-area tap water strain was most resistant. Among hydrogen peroxide systems, no statistically significant difference in Acanthamoeba survival existed with taurine inclusion.
Conclusions:
Recent clinical and tap water Acanthamoeba strains, representing proven human pathogens and/or household strains, were highly virulent against contact lens solutions. The Chicago-area tap water strain was most resilient, a concern if tap water is contributing to the AK increase. Results further differentiated resistance among T4 strains, highlighting the importance of multiple strain testing.
Insights
Contact lens solutions were ineffective against Acanthamoeba keratitis (AK) strains. Even hydrogen peroxide systems showed limited efficacy, with tap water isolates proving most resistant, raising concerns about household water contamination.
Area of Science:
- Ophthalmology
- Microbiology
- Infectious Diseases
Background:
- Acanthamoeba keratitis (AK) cases have increased, with some linked to specific contact lens solutions.
- Multipurpose solutions (MPSs) differ in composition, with some containing taurine and hydroxypropyl methylcellulose.
Purpose of the Study:
- To evaluate contact lens solution efficacy against recent Acanthamoeba clinical and tap water isolates.
- To determine if taurine in solutions affects Acanthamoeba survival.
Main Methods:
- Acanthamoeba T4 trophozoites were exposed to various contact lens solutions (MPSs and hydrogen peroxide systems) for 6 and 24 hours.
- Survival was assessed by observing growth on agar plates over one week.
- Tap water and clinical isolates were tested, including a Chicago-area tap water strain.
Main Results:
- Multipurpose solutions showed 100% Acanthamoeba survival after 6-hour exposure.
- Hydrogen peroxide systems demonstrated partial efficacy, with lower survival rates.
- The tap water Acanthamoeba strain exhibited the highest resistance to the tested solutions.
Conclusions:
- Recent Acanthamoeba strains are highly virulent against common contact lens solutions.
- Tap water may be a significant source of Acanthamoeba contributing to AK outbreaks.
- Testing multiple Acanthamoeba strains is crucial for accurate efficacy assessment.
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