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. 2016 Jul 12;7:1063. doi: 10.3389/fmicb.2016.01063

FIGURE 1.

FIGURE 1

Evaluation of Staphylococcus spp. in terms of their adherence to human fibronectin, their internalization and their persistence in MG63 cells. (A) Quantification of the fibronectin adhesion capacity of 15 Staphylococcus spp. reference strains. All of the results are expressed as percentages of the values obtained for the S. aureus 8325-4 strain. The horizontal bars denote the means derived from three independent experiments performed in quadruplicate. The fibronectin adhesion capacity of the SNA strains was compared to that of Δfnb S. aureus using the one-tailed Mann–Whitney test with an α risk of 0.05. (∗∗∗p < 0.001; SNA: Staphylococcus non-aureus). (B) MG63 cells were infected for 2 h at 37°C with staphylococci at a multiplicity of infection (MOI) of 100:1 for all strains. The invasion and persistence capacities were assessed by quantifying the viable intracellular bacterial loads at 3 h and 24 h post-infection after gentamicin treatment. Bars represent means ± standard deviations derived from three experiments performed in triplicate, and the results are expressed as the percentages of initial inoculum internalized. (C) Quantifications of LDH release, reflecting cytotoxicity, were performed on culture supernatants at 24 h post-infection. All of the results are expressed as the percentages of the values obtained for the control “uninfected cells” (100%), represented by the red line. Bars represent means ± standard deviations derived from three experiments performed in triplicate. The increase in the LDH concentration in the cells infected with an SNA strain compared to the uninfected control cells was evaluated using a one-tailed Mann–Whitney test with an α risk of 0.05 (∗∗∗p < 0.001; LDH: lactate dehydrogenase; SNA: Staphylococcus non-aureus; pi: post-infection).