Figure 1

PI-PLC enhances the invasion and persistence of Staphylococcus aureus in human keratinocytes. Gentamicin protection assays were performed to quantify the ability of wild-type and Δplc mutant strains (a–c) or Δplc :: plc and Δplc :: plc-MT strains (d–f) to invade and persist in HaCaT cells (a,c,d,f) and human epidermal keratinocytes (b,e). (a,b,d,e) Relative CFUs were measured immediately after infection (0 h) or at 24 h after infection [CFU of wild-type at 0 h = 1 (a). CFU of wild-type at 24 h = 1 (b). CFU of Δplc :: plc at 0 h = 1 (d). CFU of Δplc :: plc at 24 h = 1 (e)]. (c,f) The growth ratio of S. aureus was calculated by dividing CFU at 24 h after infection by CFU immediately after infection. N = 10 in wild-type, Δplc, Δplc :: plc, and Δplc :: plc-MT strains (a,c,d,f). N = 4 in wild-type,Δplc, Δplc :: plc, and Δplc :: plc-MT strains (b,e). Individual data values are represented by a single symbol on the box plots. Statistical significance was assessed using the Welch’s t test. *p < 0.05. **p < 0.01. ***p < 0.001. S. aureus from 10 (a,c,d,f) or 4 (b,e) distinct colonies was used for the experiments. Results are representative of two trials (a–f).