title: Contact lens care solution killing efficacy against Acanthamoeba castellanii by in vitro testing and live-imaging.
abstract: In the past decade there has been an increased incidence of Acanthamoeba keratitis, particularly in contact lens wearers. The aim of this study was to utilize in vitro killing assays and to establish a novel, time-lapse, live-cell imaging methodology to demonstrate the efficacy of contact lens care solutions in eradicating Acanthamoeba castellanii (A. castellanii) trophozoites and cysts. Standard qualitative and quantitative in vitro assays were performed along with novel time-lapse imaging coupled with fluorescent dye staining that signals cell death. Quantitative data obtained demonstrated that 3% non-ophthalmic hydrogen peroxide demonstrated the highest percent killing at 87.4% corresponding to a 4.4 log kill. The other contact lens care solutions which showed a 72.9 to 29.2% killing which was consistent with 4.3-2.8 log reduction in trophozoite viability. Both analytical approaches revealed that polyquaternium/PHMB-based was the least efficacious in terms of trophicidal activity. The cysticidal activity of the solutions was much less than activity against trophozoites and frequently was not detected. Live-imaging provided a novel visual endpoint for characterizing the trophocidal activity of the care solutions. All solutions caused rapid rounding or pseudocyst formation of the trophozoites, reduced motility and the appearance of different morphotypes. Polyquaternium/alexidine-based and peroxide-based lens care system induced the most visible damage indicated by significant accumulation of debris from ruptured cells. Polyquaternium/PHMB-based was the least effective showing rounding of the cells but minimal death. These observations are in keeping with care solution biocides having prominent activity at the plasma membrane of Acanthamoeba.
authors.affiliation: Texas Eye Research and Technology Center, University of Houston, College of Optometry, Houston, TX, United States.
authors.forename: Satya Sree N
authors.initials: SS
authors.lastname: Kolar
authors.affiliation: Texas Eye Research and Technology Center, University of Houston, College of Optometry, Houston, TX, United States.
authors.forename: Joseph C
authors.initials: JC
authors.lastname: Manarang
authors.affiliation: Texas Eye Research and Technology Center, University of Houston, College of Optometry, Houston, TX, United States.
authors.forename: Alan R
authors.initials: AR
authors.lastname: Burns
authors.affiliation: University of the Incarnate Word, Rosenberg School of Optometry, San Antonio, TX, United States.
authors.forename: William L
authors.initials: WL
authors.lastname: Miller
authors.affiliation: Texas Eye Research and Technology Center, University of Houston, College of Optometry, Houston, TX, United States.
authors.forename: Alison M
authors.initials: AM
authors.lastname: McDermott
authors.affiliation: Texas Eye Research and Technology Center, University of Houston, College of Optometry, Houston, TX, United States. Electronic address: jbergmanson@optometry.uh.edu.
authors.forename: Jan P G
authors.initials: JP
authors.lastname: Bergmanson
mesh_terms: D015823:Acanthamoeba Keratitis / Q000517:prevention & control; D048248:Acanthamoeba castellanii / Q000187:drug effects* / Q000254:growth & development; D000562:Amebiasis / Q000517:prevention & control; D000563:Amebicides / Q000494:pharmacology*; D000818:Animals; D001645:Biguanides / Q000494:pharmacology; D018639:Contact Lens Solutions / Q000494:pharmacology*; D004203:Disinfection / Q000379:methods; D004338:Drug Combinations; D006861:Hydrogen Peroxide / Q000494:pharmacology; D021261:Parasitic Sensitivity Tests; D011108:Polymers / Q000494:pharmacology; D011437:Propylamines / Q000494:pharmacology; D012015:Reference Standards; D053058:Trophozoites / Q000187:drug effects / Q000254:growth & development
chemical_list: D000563:Amebicides; D001645:Biguanides; D018639:Contact Lens Solutions; D004338:Drug Combinations; D011108:Polymers; D011437:Propylamines; C031233:polihexanide; C058655:polyquaternium 1; D006861:Hydrogen Peroxide; C001570:alexidine; C401661:myristamidopropyl dimethylamine
keywords: Acanthamoeba; Care solution; Contact lens; Live imaging