Premium
Biguanide‐induced changes in Acanthamoeba castellanii : an electron microscopic study
Author(s) -
Watcharee Khunkitti,
A. C. Hann,
David Lloyd,
J. R. Furr,
A. D. Russell
Publication year - 1998
Publication title -
journal of applied microbiology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.889
H-Index - 156
eISSN - 1365-2672
pISSN - 1364-5072
DOI - 10.1046/j.1365-2672.1997.00305.x
Subject(s) - biguanide , ultrastructure , intracellular , cytoplasm , cell wall , chlorhexidine , chemistry , acanthamoeba , microbiology and biotechnology , biocide , cell membrane , cell damage , transmission electron microscopy , biophysics , biology , cell , biochemistry , materials science , anatomy , medicine , nanotechnology , metformin , organic chemistry , diabetes mellitus , endocrinology , dentistry
Trophozoites and cysts of Acanthamoeba castellanii were exposed to chlorhexidine diacetate (CHA) and polyhexamethylene biguanide (PHMB); changes in cell ultrastructure and surface structure were examined by both transmission and scanning electron microscopy. PHMB caused a greater degree of structural and membrane damage; the cytoplasmic contents were severely depleted and there were clusters of densely stained precipitates on the cell surface. Concentrations of CHA greater than 100 μg ml −1 produced shrinkage from the cyst wall. At high concentrations, PHMB induced a slight withdrawal of the cytoplasm from the wall and, unlike CHA, induced swelling of the cysts. These findings do not define the mechanisms of action of CHA and PHMB, but provide evidence that a major target site for both agents is the plasma membrane. However, additional intracellular damage undoubtedly contributes to the lethal effects. The greater resistance of cysts may be associated with reduced biguanide uptake.