The indicated strains of C. difficile harboring the PtcdA::rfp reporter plasmid were fixed at (A) OD600 ~0.5, (B) OD600 ~1.0 and (C) after 20 hours of growth. Percentages refer to the fraction of cells that were TcdA-ON (mean ± st. dev., n = at least 3 independent experiments). The strains shown represent the following ribotypes: CD196 (ribotype 027), R20291 (ribotype 027), CD630Δerm (ribotype 012), JIR8094 (ribotype 012), NAP07 (ribotype 078), NAP08 (ribotype 078) and VPI10463 (ribotype 087).