Time-course analysis of growth (A) and rate of DNA replication (B) was performed in SA13011-HeR −/+ OXA (0.5 µg/ml) during β-lactam-induced HeR/HoR selection.

<p>Bacteria were grown −/+ OXA (0.5 µg/ml) overnight. Cultures without OXA (HeR) were then diluted to an optical density at 600 nm (OD₆₀₀) equivalent to the culture growing with OXA (HoR) and continued to grow at 37°C with shaking. (B) Both SA13011-HeR/-HoR cultures were supplemented with the radioactive methyl-[3H]-thymine precursor (1 µCi/ml); triplicates samples were removed at different time-intervals and collected for DNA extraction, eluted and transferred to Whatman paper filters; after drying, radioactivity was measured by liquid scintillation. Values represent the means of three biological replicates ± standard error of the mean (SEM), sampled in triplicate to minimize error by inter- and intra-samples, respectively.