Fig 5.

Affinity of fluorescently labeled colistin with bacteria. (A) A. baumannii LAC-4 WT or LAC-4 ColR was cultured to mid-log phase in MHII or RPMI-1640. Following incubation with BoDipy-labeled colistin (0.1 mg/L), we measured fluorescence by flow cytometry. Controls included Proteus mirabilis 10195 and unstained samples of each bacterial strain. (B) A. baumannii LAC-4 WT or LAC-4 ColR strains were cultured to mid-log phase in MHII, RPMI-1640, or MHII supplemented with 25 mM sodium bicarbonate. Bacteria were incubated with Dansyl-labeled polymyxin B (30 mg/L), and fluorescence was measured by flow cytometry.