title: Amoebicidal effects of contact lens disinfecting solutions.
abstract: OBJECTIVE
  To compare the traditional manual hemacytometer method and an automated counter (Vi-cell) to enumerate and distinguish between viable and non-viable amoeba, and to determine the efficacies of contact lens (CL) disinfecting solutions against three species of Acanthamoeba. The efficacies in the presence of a bacterial food source and bovine serum albumin (BSA) were investigated.
  
  
  METHODS
  Four brands of multipurpose solutions and a hydrogen peroxide disinfecting system (Oxysept) for soft CLs, and four disinfecting solutions for Rigid Gas Permeable (RGP) lenses were tested against three species of Acanthamoeba. Page's amoebic saline was included as a negative control and standard solutions of disinfecting agents, 6% hydrogen peroxide and 0.5% chlorhexidine, as positive controls. The effects of the presence of Pseudomonas aeruginosa and BSA on effectiveness were assessed.
  
  
  RESULTS
  None of the CL solutions tested achieved a 1-log reduction in viability of all three Acanthamoeba species within the manufacturer's recommended disinfection times. The presence of P. aeruginosa did not significantly affect disinfecting capacity of multipurpose solution solutions but reduced activity of RGP solutions and the hydrogen peroxide system. BSA reduced trophozoicidal activity of all solutions. Bland and Altman analysis showed good agreement between Vi-cell and hemacytometer.
  
  
  CONCLUSIONS
  The Vi-Cell analyzer offers a simple and effective method of determining amoebicidal activity. Our results show that the CL solutions tested could not satisfactorily kill Acanthamoeba.
authors: Department of Health Technology and Informatics, The Hong Kong Polytechnic University, Hong Kong SAR, China. htmboost@polyu.edu.hk
authors: Maureen V
authors: MV
authors: Boost
authors: Guang-Sen
authors: GS
authors: Shi
authors: Sindy
authors: S
authors: Lai
authors: Pauline
authors: P
authors: Cho
mesh_terms: D000048:Acanthamoeba / Q000187:drug effects* / Q000302:isolation & purification; D015823:Acanthamoeba Keratitis / Q000469:parasitology / Q000517:prevention & control*; D000563:Amebicides / Q000494:pharmacology*; D000818:Animals; D018639:Contact Lens Solutions / Q000494:pharmacology*; D003263:Contact Lenses, Hydrophilic / Q000469:parasitology*; D004202:Disinfectants / Q000494:pharmacology*; D004203:Disinfection / Q000379:methods*; D006801:Humans
chemical_list: D000563:Amebicides; D018639:Contact Lens Solutions; D004202:Disinfectants