Percentage of viable, early apoptotic, late apoptotic/necrotic KYSE-450 cells after incubation with different concentrations of F. gastrosuis lysate (A) and viable F. gastrosuis bacteria (B). Data are shown as the average (4 strains, 3 replications per strain) percentages of viable, early apoptotic and late apoptotic/necrotic KYSE-450 cells with standard deviation. A The cells were incubated for 24, 36, 48 and 72 h with 50, 200 and 500 µg F. gastrosuis lysate (4 strains). B The cells were incubated for 2, 6 and 12 h with 5, 20 and 50 MOI viable F. gastrosuis bacteria (4 strains). The percentage late apoptotic/necrotic cells (i.e. Annexin-V-FITC positive and PI positive) contains a small subpopulation of Annexin-V-FITC negative and PI positive cells defined as late necrotic cells. See Additional files 15, 16 for more detailed information.