Cytopathogenic effect caused by Bacteroides fragilis endotoxin

The influence of Bacteroides fragilis ssp. fragilis NCTC 9343 and 62/73 endotoxins and Escherichia coli O26:B6 lipopolysaccharide on human embryo fibroblast cultures was examined. Different endotoxin dilutions were added to the suspension of fibroblasts in culture medium containing 2--3 x 10(5) cells 1 ml. Results were recorded at 24-th intervals for 96 h. The viability of the cells and morphological and cytological changes were determined. The both tested endotoxins from strains of Bacteroides fragilis produced in cultures of human embryo fibroblasts morphological and cytological changes, analogous to those observed under the action of Escherichia coli O26:B6 endotoxin. The intensity of the changes depended on the concentration and time of action of the endotoxin. The examined endotoxins added to the tissue cultures inhibited cells growth. Cell polymorphism, formation of syncytia, the appearance of intracytoplasmic and intranuclear inclusions, cytoplasm vacuolisation and reduction of the number of nucleoli were observed.