title: Cysticidal effect on acanthamoeba and toxicity on human keratocytes by polyhexamethylene biguanide and chlorhexidine.
abstract: OBJECTIVE
  To evaluate the cysticidal effect of polyhexamethylene biguanide (PHMB) and chlorhexidine on Acanthamoeba and its toxic effect on cultured human keratocytes.
  
  
  METHODS
  Each well of a twofold-diluted Acanthamoeba cyst-containing suspension of 5 x 10(4) cysts/mL was treated with PHMB and chlorhexidine for 8, 24, and 48 hours to determine the minimal cysticidal concentration (MCC) of each disinfectant. Human corneal keratocytes (5 x 10(4) cells/mL) were exposed to PHMB and chlorhexidine for the same time to determine the survival rate of keratocytes. Inverted phase-contrast and electron microscopy were used to observe the morphologic changes.
  
  
  RESULTS
  The mean MCC of PHMB for 8, 24, and 48 hours was 9.42, 5.62, and 2.37 microg/mL, respectively. The mean MCC of chlorhexidine for 8, 24, and 48 hours was 24.32, 10.02, and 7.02 microg/mL, respectively. The respective survival rate of keratocytes at the MCC was 91.7%, 64.6%, and 49.7% for PHMB and 95.7%, 90.6%, and 78.1% for chlorhexidine, respectively. The cysts and keratocytes showed more damaged appearances after treatment with PHMB than chlorhexidine.
  
  
  CONCLUSIONS
  PHMB and chlorhexidine showed a similar amoebicidal efficacy. However, PHMB seemed to be more toxic to keratocytes than chlorhexidine.
authors.affiliation: Department of Ophthalmology, Pusan National University Hospital, Pusan, Korea.
authors.forename: Ji-Eun
authors.initials: JE
authors.lastname: Lee
authors.forename: Boo Sup
authors.initials: BS
authors.lastname: Oum
authors.forename: Hee Young
authors.initials: HY
authors.lastname: Choi
authors.forename: Hak Sun
authors.initials: HS
authors.lastname: Yu
authors.forename: Jong Soo
authors.initials: JS
authors.lastname: Lee
mesh_terms: D048248:Acanthamoeba castellanii / Q000187:drug effects* / Q000648:ultrastructure; D000563:Amebicides / Q000633:toxicity*; D000818:Animals; D001645:Biguanides / Q000633:toxicity*; D002470:Cell Survival; D002478:Cells, Cultured; D002710:Chlorhexidine / Q000633:toxicity*; D003319:Corneal Stroma / Q000187:drug effects* / Q000648:ultrastructure; D004202:Disinfectants / Q000633:toxicity*; D005347:Fibroblasts / Q000187:drug effects / Q000648:ultrastructure; D006801:Humans; D046529:Microscopy, Electron, Transmission; D008858:Microscopy, Phase-Contrast; D021261:Parasitic Sensitivity Tests
chemical_list: D000563:Amebicides; D001645:Biguanides; D004202:Disinfectants; C031233:polihexanide; D002710:Chlorhexidine