Extended Data Fig. 2: Antibiotic-resistance profile of key strains.
From: Salmonella persisters promote the spread of antibiotic resistance plasmids in the gut
Antibiotic susceptibility testing was performed in LB in 96-well plates. Six strains (indicated on the figure axes) were tested against seven antibiotics, grown at 37 °C at 120 r.p.m. for 16 h, at which point the OD600 nm was measured. For each antibiotic, the highest concentration used was based on the working concentration in this study. For example, the concentration of antibiotic used for selective plating in the case of streptomycin, kanamycin, ampicillin and chloramphenicol (the highest concentration of chloramphenicol was fivefold-higher than the concentration used for selective plating, because this was already close to the minimum inhibitory concentration), or the concentration of antibiotic used for the gentamicin protection assay. Importantly, a very low minimum inhibitory concentration was observed for antibiotics used in vivo to enrich for persisters (that is, ciprofloxacin and ceftriaxone). The mean of three experiments is presented on a blue–white colour gradient, in which blue indicates a large amount of bacterial growth. This is calculated by subtracting the OD600 nm measured for each sample well from the background generated by the medium.
