Fig. 1: A dilution-regrowth-based screen identifies compounds that delay the regrowth of stationary-phase UPEC.
From: Antibacterial compounds against non-growing and intracellular bacteria
A Schematic of the screening assay. A 24-h culture of UPEC strain CFT073 was dispensed into a microtiter plate and treated with 20 μM compounds from the collection for 24 h. The samples were then diluted 2500-fold into drug-free CA-MHB (pH 7.4), and OD600 was measured after 6 h. B Regrowth delay following bactericidal treatment. For assay validation, UPEC CFT073 was cultivated for 24 h in 1:4 diluted CA-MHB (pH 7.4) and treated for 24 h with 20 μM gatifloxacin (GAT) or finafloxacin (FIN), which kill non-growing bacteria and served as positive controls for screening. After a 2500-fold dilution into drug-free CA-MHB, the regrowth of the drug-treated samples was delayed compared to that of the drug-free control (DMSO). C, D Screening of the combined Prestwick and SPECS collections identified drugs that delayed bacterial regrowth in 1:4 diluted CA-MHB (pH 7.4) (C) and LPM (pH 5.5) (D). A cutoff of OD600 < 0.1 (dashed line) was used to identify hits (red). Most of the tested compounds (black) showed no effect compared to the drug-free control (purple). GAT (green) and FIN (blue) were included as positive controls in each plate. E Pie chart illustrating the distribution of validated hits across different drug groups. F Venn diagram depicting the overlap of validated hits identified in 1:4 CA-MHB (pH 7.4) and LPM (pH 5.5).
