Cytotoxicity induced by C. difficile toxins in CDI patient sera.
Cell rounding was observed under microscopy in two serum samples from Case I (A, A’) and Case II (B, B’) by cell-based assay on mRG1-1 cells (A, B) and Vero cells (A’, B’). Cells cultured in medium were as negative controls. TcdA (50 pg/ml with A1H3)-treated mRG1-1 cell and TcdB (25 pg/ml)-treated Vero cell were served as positive controls. The sera (1:10 dilution) were added to cells and cell morphology changes were observed under a phase-contrast microscope.