title: Flow cytometry for determination of the efficacy of contact lens disinfecting solutions against Acanthamoeba spp.
abstract: Flow cytometric analyses of cellular staining with fluorescent viability dyes and direct microscopic observations of methylene blue exclusion were compared for evaluation of the effects of a chlorhexidine gluconate-based contact lens disinfectant solution and a polyhexamethylene biguanide solution against cysts and trophozoites of Acanthamoeba castellanii and Acanthamoeba polyphaga. The flow cytometric procedure with propidium iodide (used to stain dead cells) indicated that more than 90% of trophozoites of both species (inocula of 10(5) to 10(6)/ml) at 22 degrees C lost their viability after 4 h of exposure to chlorhexidine. When propidium iodide was used in combination with fluorescein diacetate (for live cells), the apparent number of propidium iodide-stained cells was reduced, but the relative efficacies of the two biguanide solutions appeared unchanged from those evident with the single dyes; the chlorhexidine solution was more effective than the polyhexamethylene biguanide solution. Similar data were obtained with the more cumbersome methylene blue exclusion procedure. Flow cytometric analyses provided a statistically reproducible and rapid procedure for determining the relative antiamoebal efficacies of the disinfecting solutions.
authors.affiliation: Department of Biology, Georgia State University, Atlanta, Georgia 30303, USA.
authors.forename: R N
authors.initials: RN
authors.lastname: Borazjani
authors.forename: L L
authors.initials: LL
authors.lastname: May
authors.forename: J A
authors.initials: JA
authors.lastname: Noble
authors.forename: S V
authors.initials: SV
authors.lastname: Avery
authors.forename: D G
authors.initials: DG
authors.lastname: Ahearn
mesh_terms: D000048:Acanthamoeba / Q000187:drug effects*; D000818:Animals; D001645:Biguanides / Q000494:pharmacology; D002710:Chlorhexidine / Q000031:analogs & derivatives / Q000494:pharmacology; D018639:Contact Lens Solutions / Q000494:pharmacology*; D005434:Flow Cytometry / Q000379:methods*; D008751:Methylene Blue / Q000494:pharmacology; D013194:Staining and Labeling / Q000379:methods
chemical_list: D001645:Biguanides; D018639:Contact Lens Solutions; C031233:polihexanide; C010882:chlorhexidine gluconate; D002710:Chlorhexidine; D008751:Methylene Blue