Journal: PLOS Pathogens
Article Title: Monitoring intracellular replication dynamics unveils high proportion of non-replicating antibiotic-tolerant Staphylococcus aureus inside osteoblasts
doi: 10.1371/journal.ppat.1013525
Figure Lengend Snippet: MG63 cells labeled (B , D) or not ( A , C , E ) with CellTracker Red CMTPX (red) were seeded at sparse (B , D) or confluent (A , C , E) density and infected and treated as previously described in (BJI035: rifampicin resistant). (A) At 2 hpi propidium iodide (PI) was added at 2 µg/mL. At 24 hpi PI fluorescence intensity was measured with a plate reader. PI fluorescence intensity is normalized to uninfected cells in untreated and rifampicin-treated conditions. (B) Time-lapse imaging was conducted over 24 hours with hourly acquisitions using automated confocal microscopy. Quantification of the S. aureus SH1000 population size per cell over time represented by the total green (GFP) pixel count normalized per cell. (C, E) Intracellular S. aureus SH1000 were collected at 1 hpi and 24 hpi, and the total number of S. aureus forming colonies on agar plate was investigated (C) as well as their area distribution frequency at 24 hpi (E) and the small colony variants rates (F) . (D) At 6 hpi, rifampicin treatment was either withdrawn by washing or maintained, and incubation continued. Time-lapse imaging was conducted over 18 hours post-withdrawal with hourly acquisitions using automated confocal microscopy. Quantification of infected cells based on intracellular S. aureus replication dynamics (RD). Results were presented either as single value and mean ± SD from 3 independent experiments (B, E) or as mean ± SD representing 9 individual values from 3 independent experiments (A , D : N = 165 infected cells, F) or 12 individual values from 4 independent experiments (C) . One-way ANOVA with Dunnett’s correction for multiple post hoc comparisons with the control (A) and Mann-Whitney test (C , D, F) : *p < 0.05, **p < 0.01, ****p < 0.0001.
Article Snippet: Infection was performed at MOI 8 (or 2 or 4 where indicated) using sparse CellTracker Red CMTPX-labeled cells in 24-well plates (4TITUDE, 4TI-0241) or 96-well plates (Greiner bio-one, 655090), as described above.
Techniques: Labeling, Infection, Fluorescence, Imaging, Confocal Microscopy, Incubation, Control, MANN-WHITNEY