Fig. 3: Salmonella DNA damage during and after exposure to enrofloxacin.
From: Limited impact of Salmonella stress and persisters on antibiotic clearance
a, Time-lapse gallery of RecA foci in enrofloxacin-exposed Salmonella. Scale bar, 1 μm. b, Snapshots of Salmonella exposed for 1 h to enrofloxacin, followed by drug washout for 30 min and incubation in LB. Scale bar, 5 μm. c, Fraction of undamaged and regrowing cells during 1 h (top), 2 h (middle) or 4 h (bottom) enrofloxacin exposure, washout and LB incubation (250 (top), 255 (middle) and 250 (bottom) cells; dotted lines show monoexponential fits for damage during exposure and washout; summary data and independent replicates in d,g). d, Fractions of undamaged cells at the end of enrofloxacin exposure, in LB, and regrowing survivors (two independent experiments, 755 and 1,233 cells). e, Snapshots of Salmonella exposed for 7 h to decreasing concentrations of enrofloxacin, followed by drug-free nutrient-poor medium (Supplementary Video 3). Scale bar, 5 μm. f, Fraction of undamaged and regrowing cells during and after 7 h exposure to decreasing concentrations of enrofloxacin (ENR) in nutrient-poor medium (276 cells; dotted lines show monoexponential fits for damage during exposure, post-antibiotic damage or baseline damage; summary data for this and two independent replicates in g). g, Fractions of regrowing cells after 4 h enrofloxacin exposure and a switch to LB (4 h/LB; 250 and 444 cells; same data as in d) or under in vivo-mimicking conditions (IVM) with declining enrofloxacin concentrations and regrowth in nutrient-poor medium (276, 271 and 378 cells). Circles represent independent experiments. Two-tailed t-test on log-transformed data. h, Fluorescence of Salmonella/pPcad-gfp or Salmonella lexA3/pPcad-gfp in untreated (0 h) or enrofloxacin-treated mice. The vertical line separates GFP+ responders from GFP− non-responders. The inset shows the median fluorescence (MFI) of GFP+ cells, the line connects the geometric means (test for non-zero slope in a linear regression of log-transformed values). The histograms represent pooled data, circles in the inset graph represent individual mice (1 h, n = 5; 3 h and 4 h, n = 4). i, Blue, fraction of GFP− non-responders in enrofloxacin-treated mice (0 h, n = 2; 1 h, n = 6; 2 h and 4 h, n = 4). Each symbol represents an individual mouse. Brown, CFUs recovered from similar samples (same data as in Fig. 1a; geometric mean ± geometric s.d.; 1 h, n = 10; 2 h, n = 3; 4 h, n = 6). Two-way ANOVA for difference between SOS response and CFU recovery. j, Contribution of responders (SOS+) and non-responders (SOS−) to CFU counts (Supplementary Note 5; data are mean ± s.d. for data from independently infected mice; 1 h, n = 6; 4 h, n = 4). Two-way ANOVA for difference between SOS+ and SOS−.
