title: Strategies to optimize conditions for testing multipurpose contact lens solution efficacy against Acanthamoeba.
abstract: OBJECTIVE
  To optimize the growth, culture, and life cycle conditions for testing multipurpose solutions (MPS) against Acanthamoebatrophozoites and cysts to better inform the development of an appropriate test protocol.
  
  
  METHODS
  Two strains of Acanthamoeba castellanii were grown using 2 different methods, bacterized and axenic. Amoebae grown from both methods and from both strains were treated with 4 different MPS as trophozoites and cysts, which were generated using 4 encystment methods. Experiments were run in triplicate with controls. A 5-tube most probable number method was used to enumerate the survivors and to determine the log kills. Statistical analysis was performed using effect screening.
  
  
  RESULTS
  There was a marked difference in effectiveness among solutions, which varied with growth conditions (P<0.0001) and encystment method. Growth medium affected survival. In addition, there was a significant difference in cyst survival, which was dependent on encystment method (P=0.0013). The strain used was less of a factor in trophozoite resistance to MPS. Cyst resistance to MPS varied depending on which strain was used, but it was not a significant factor.
  
  
  CONCLUSIONS
  When designing a contact lens solution efficacy testing protocol for Acanthamoeba, care should be taken to control for variables that may distort results. An appropriate protocol should include growing Acanthamoeba bacterized and allowing them to encyst naturally. By choosing optimized testing conditions, a more realistic efficacy of contact lens solutions can be determined which will result in better and safer products on the market.
authors.affiliation: Division of Biology, Food and Drug Administration, Food and Drug Administration, Center for Devices and Radiological Health, Office of Device Evaluation, Silver Spring, MD, USA. mshoff@hodges.edu
authors.forename: Megan E
authors.initials: ME
authors.lastname: Shoff
authors.forename: Malvina B
authors.initials: MB
authors.lastname: Eydelman
mesh_terms: D015823:Acanthamoeba Keratitis / Q000469:parasitology / Q000517:prevention & control; D048248:Acanthamoeba castellanii / Q000187:drug effects* / Q000254:growth & development; D015169:Colony Count, Microbial; D018639:Contact Lens Solutions / Q000494:pharmacology*; D046508:Culture Techniques / Q000379:methods*; D004202:Disinfectants / Q000494:pharmacology
chemical_list: D018639:Contact Lens Solutions; D004202:Disinfectants