W. Khunkitti et al., THE LETHAL EFFECTS OF BIGUANIDES ON CYSTS AND TROPHOZOITES OF ACANTHAMOEBA-CASTELLANII, Journal of Applied Bacteriology, 81(1), 1996, pp. 73-77
The effects of a range of biocides on trophozoite and encysted forms o
f Acanthamoeba castellanii were investigated. Viable acanthamoebae wer
e enumerated by a plaque assay technique. The cyst form of Acanthamoeb
a castellanii was more resistant to all biocides tested than the troph
ozoite form. Of the biocides tested, chlorhexidine diacetate (CHA) and
polyhexamethylene biguanide (PHMB) were the most effective. Their let
hal effects were time- and concentration-dependent. CHA was very effec
tive when formulated in 0.1% EDTA combined with Tris buffer pH 7.8 whe
reas PHMB activity was reduced by 0.1% EDTA. Three per cent dimethylsu
lphoxide (DMSO) enhanced the activity of CHA but not of PHMB.