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. 2022 Jun 7;11:e74062. doi: 10.7554/eLife.74062

Figure 2. Correlation between antibiotic efficacy and antibiotic accumulation.

Temporal patterns of elongation rate during exposure to the fluorescent derivative of roxithromycin for (A) five representative E. coli bacteria that accumulated the drug and (B) five representative E. coli bacteria that did not accumulate the drug. The fluorescent derivative of roxithromycin was delivered at t=0 at a concentration of 46 µg mL–1 and was dissolved in lysogeny broth (LB), circles and arrows indicate t0, the time point at which each bacterium started to accumulate the drug (i.e. bacterial fluorescence signal became distinguishable from the background). (C) Correlation between each bacterium t0 and its average elongation rate throughout exposure to the fluorescent derivative of roxithromycin (i.e. 0<t< 8100 s). r is the Pearson coefficient quantifying the correlation above, ***: p-value<0.001, N=52 bacteria. (D) Average elongation rates for bacteria that had not yet started (before uptake) or had started (after uptake) accumulating the fluorescent derivative of roxithromycin, as well as for bacteria that did not accumulate the drug (no uptake). The red dashed and blue dotted lines within each violin plot represent the median and quartiles of each data set, respectively. Paired t-test between elongation rates before and after onset in accumulation: ****: p-value<0.0001, N=36 pairs. Unpaired t-test between the elongation rates of bacteria that did not take up the drug compared to the elongation rate of bacteria that had not yet started taking up the drug: not significant, p-value=0.07, N=13 and 36 bacteria, respectively. Unpaired t-test between the elongation rates of bacteria that did not take up the drug compared to the elongation rate of bacteria that had started taking up the drug: ****: p-value<0.0001, N=13 and 36 bacteria, respectively.

Figure 2—source data 1. Single-cell elongation rates during roxithromycin treatment.
Temporal patterns of elongation rate during exposure to the fluorescent derivative of roxithromycin for five representative E. coli bacteria that accumulated the drug and five representative E. coli bacteria that did not accumulate the drug. The fluorescent derivative of roxithromycin was delivered at t=0 at a concentration of 46 µg mL–1 and was dissolved in lysogeny broth (LB).
Figure 2—source data 2. Correlation between drug accumulation and efficacy.
Correlation between each bacterium t0 and its average elongation rate throughout exposure to the fluorescent derivative of roxithromycin.
Figure 2—source data 3. Average elongation rates for bacteria that had not yet started ccumulating the fluorescent derivative of roxithromycin.
Figure 2—source data 4. Average elongation rates for bacteria that had started accumulating the fluorescent derivative of roxithromycin.
Figure 2—source data 5. Average elongation rates for bacteria that did not accumulate the fluorescent derivative of roxithromycin.

Figure 2.

Figure 2—figure supplement 1. Interdependence between single-cell elongation rate before treatment and single-cell elongation rate during exposure to (A) roxithromycin-NBD and (B) unlabelled roxithromycin.

Figure 2—figure supplement 1.

r is the Pearson correlation coefficient, *: p-value<0.05, ***: p-value<0.001. N=46 and 51 individual E. coli investigated and collated from biological triplicate. In each experiment E. coli was grown for 2 hr in the microfluidic device with continuous supply of fresh lysogeny broth (LB). During this 2 hr growth period the elongation rate of each bacterium was measured between consecutive time points and the average elongation rate for each bacterium was calculated. At the end of this 2 hr growth period, 46 µg mL–1 roxithromycin-NBD or unlabelled roxithromycin dissolved in LB was continuously delivered for a 4 hr treatment period in the microfluidic device. During this 4 hr treatment period the elongation rate of each bacterium was measured as indicated above. The data in (A) are reproduced from Figures 2C and 4A.