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. Author manuscript; available in PMC: 2022 Jun 12.
Published in final edited form as: Nature. 2021 Oct 13;599(7883):120–124. doi: 10.1038/s41586-021-03986-2

Figure 2. Macrolides and tetracyclines kill some human gut commensal species.

Figure 2

a. The survival of 12 abundant human gut microbial species was measured after 5h treatment with erythromycin, azithromycin or doxycycline at 5-fold MIC concentrations (mean+SD of 3 independent experiments). CFUs/ml before treatment were set to 100%. Absolute values are indicated next to strain abbreviations – Bf: B.fragilis; Bu: B.uniformis; Bt: B.thetaiotaomicron; Bo: B.ovatus; Bc: B.caccae; Bv: B.vulgatus; Pc: P.copri; Ec: E.coli ED1a; Fn: F.nucelatum; Cb: C.bolteae; Er: E.rectale; Ri: R.intestinalis. Shaded area denotes bactericidal threshold; nd "not detected" (detection limit: 1 CFU/ml); “*“ resistant strains. Species are plotted according to phylogeny.

b. Erythromycin causes lysis in B. vulgatus and B. uniformis. Strains were grown for 3h (arrow) before adding (orange) or not (black) 15 μg/ml erythromycin (5-fold MIC). Growth curves depict mean±SD (dashed line) of 3 independent experiments.

c. Erythromycin induces blebbing, cytoplasmic shrinkage and lysis (white arrows) in B. vulgatus and B. uniformis. Represenative images of phase contrast videos (Supplementary Material) acquired after erythromycin treatment; scale bar5 μm.

d. The commensal E. coli ED1a is more susceptible to doxycycline killing than lab E. coli (BW25113), despite both strains having same MIC (4 μg/ml). Survival of E. coli strains was measured in monocultures or as part of 12-member communities (all species from panel a) after 5h treatment with 5-fold MIC doxycycline (mean±SD of 3-6 independent experiments). CFUs/ml before treatment were set to 100%.

e.E. coli ED1a, but not BW25113, is eliminated from community after two rounds of doxycycline treatment. A 12-member community (same as d) containing either E. coli ED1a or BW25113 was treated with doxycycline for 5h (5-fold E. coli MIC), washed with PBS, treated again with doxycycline, and re-grown in MGAM. CFUs/ml were counted to assess community (dashed lines) and E. coli (solid lines) survival - shown the mean±SD of 3 independent experiments.