Cysticidal effect on acanthamoeba and toxicity on human keratocytes by polyhexamethylene biguanide and chlorhexidine.
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.
Lee
Ji-Eun
JE
Department of Ophthalmology, Pusan National University Hospital, Pusan, Korea.
Oum
Boo Sup
BS
Choi
Hee Young
HY
Yu
Hak Sun
HS
Lee
Jong Soo
JS
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
D000563:Amebicides; D001645:Biguanides; D004202:Disinfectants; C031233:polihexanide; D002710:Chlorhexidine