Fig. 7.

Biofilm formation of S. aureus strains SA113, Newman HOM, and Newman D2C HOM in TSB-HBS or RPMI-1640 under static conditions. (a,b) Exponential growth phase cells of strains SA113 (red bars), Newman HOM (orange bars), and Newman D2C HOM (turquoise bars) were inoculated into TSB supplemented with 5% human blood serum (TSB-HBS; a) or Roswell Park Memorial Institute 1640 medium (RPMI-1640; b) and cultured in Nunclon Delta-treated 96-well microplates for 18 h at 37 °C under static conditions. Washing steps prior to the safranin staining were performed as indicated. (a,c) Representative images of safranin-stained vegetation. (b,d) A₅₃₀ readings of safranin contents in the wells after solubilization with 30% acetic acid. Results represent the averages of six to nine independent experiments done in duplicate. Error bars indicate the standard deviation of the mean. Round symbols indicate the mean A₅₃₀ values of individual experiments. *p < 0.05; ** p < 0.01 (Kruskal–Wallis test and Dunn’s multiple comparison test).