Related Experiment Video
Updated: Jul 23, 2026
10:56
Complementary Use of Microscopic Techniques and Fluorescence Reading in Studying Cryptococcus-Amoeba Interactions
Published on: June 22, 2019
Biguanide-induced changes in Acanthamoeba castellanii: an electron microscopic study
W Khunkitti1, A C Hann, D Lloyd
1Welsh School of Pharmacy, School of Molecular and Medical Biosciences, University of Wales Cardiff, Cardiff, UK.
Journal of Applied Microbiology
|July 13, 2004
Summary
Polyhexamethylene biguanide (PHMB) and chlorhexidine diacetate (CHA) damage Acanthamoeba castellanii, primarily targeting the plasma membrane. PHMB caused more severe damage than CHA, though cyst resistance suggests reduced biguanide uptake.
Area of Science:
- Microbiology
- Cell Biology
- Biochemistry
Background:
- Acanthamoeba castellanii are opportunistic pathogens causing serious infections.
- Antimicrobial agents like chlorhexidine diacetate (CHA) and polyhexamethylene biguanide (PHMB) are used to treat Acanthamoeba infections.
- Understanding their mechanisms of action is crucial for effective treatment.
Purpose of the Study:
- To investigate the ultrastructural and surface changes in Acanthamoeba castellanii trophozoites and cysts exposed to CHA and PHMB.
- To compare the efficacy of CHA and PHMB in damaging Acanthamoeba castellanii.
- To identify potential target sites of these biocides.
Main Methods:
- Exposure of Acanthamoeba castellanii trophozoites and cysts to varying concentrations of CHA and PHMB.
- Examination of cellular and surface structures using transmission electron microscopy (TEM) and scanning electron microscopy (SEM).
Main Results:
- PHMB induced more significant structural and membrane damage, including cytoplasmic depletion and surface precipitates.
- CHA concentrations above 100 µg/mL caused trophozoites to shrink from the cyst wall.
- PHMB caused cyst swelling and cytoplasmic withdrawal, indicating differential effects on cyst and trophozoite stages. Cysts showed greater resistance, possibly due to reduced biguanide uptake.
Conclusions:
- The plasma membrane is a primary target for both CHA and PHMB against Acanthamoeba castellanii.
- Intracellular damage contributes to the lethal effects of these biocides.
- The differential effects and cyst resistance highlight the complexity of Acanthamoeba's response to disinfectants.
