Fig. 1: Checkerboard analyses for the evaluation of the synergy between potentiators and antibiotics. | Communications Biology

Fig. 1: Checkerboard analyses for the evaluation of the synergy between potentiators and antibiotics.

From: The membrane-active polyaminoisoprenyl compound NV716 re-sensitizes Pseudomonas aeruginosa to antibiotics and reduces bacterial virulence

Fig. 1

a–c Detailed analysis for PAO1. a Change in the MICs of 4 antibiotics in the presence of NV716 at increasing concentrations. b Determination of the corresponding FIC indexes (FICI) in a heatmap plot. c Checkerboard plate having allowed to determine FICI for the combination of NV716 and rifampicin. The gray scale shows the A620 nm in percentage of the maximal value. The other panels show heatmaps describing FICI of potentiators for reference strains in combination with (d–g) abandoned antibiotics (DOX doxycycline, CHL chloramphenicol, RIF rifampicin) and ciprofloxacin (CIP), calculated for concentrations of 2.5 μM alexidine, 0.5 µM colistin (CST), 30 µM PMBN, 38 µM PAβN, 2.5 μM NV731 and 2.5 μM NV716; or with (h–k) ampicillin (AMP) or antibiotics active against Gram-positive bacteria (LZD linezolid, VAN vancomycin, AZI azithromycin), calculated for concentrations of 38 µM PAβN, 2.5 μM NV731, 2.5 mM and 10 μM NV716; or for 4 colistin-resistant isolates25 vs. PAO1 (l–o, with colistin MICs are shown on the left) combined with the same antibiotics as in d–g and calculated for concentrations of 38 µM PAβN, 30 µM PMBN, or 2.5 or 10 µM NV716. Synergy is defined as FICI < 0.5 (appearing in green on the graphs). All data are mean from at least two independent experiments. PT629: MexAB overproducer derivative of PAO1; PAO1mexAB: PAO1 derivative deleted for the expression of mexAB; PAO509: PAO1 derivative deleted for the expression of 5 RND efflux transporters; PA313, PA2938, PA307, PA272: colistin-resistant isolates.

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