X-ray microanalysis of chlorine and phosphorus content in biguanide-treated Acanthamoeba castellanii

Energy dispersive analysis of X-rays (EDAX) was used to study the effects o f chlorhexidine diacetate (CHA) and polyhexamethylene biguanide (PHMB) on A canthamoeba castellanii. A high variation of elements occurred in untreated individual cells and only two elements, Cl (a biocide marker) and P, were investigated. X-ray dot mapping of untreated trophozoites and cysts reveale d that Cl in cells was uniformly distributed throughout the cytoplasm, wher eas P was less dense in the vacuoles. X-ray dots of Cl in biocide-treated t rophozoites and cysts appeared denser and evenly distributed within the cel ls as the biguanide concentration increased. Quantitative analysis of eithe r CHA or PHMB within the cells using Cl as an elemental marker was unsatisf actory because of the high Cl levels in untreated cells. The apparent incre ases of P in some experiments with treated cells might be associated with r educed permeability, protein coagulation or aggregation of phospholipids.