Figure 1.
Time-killing assays of Pseudomonas aeruginosa. Time-killing assays were performed using 4 and 8 μg/mL of polymyxin B for PAO1 (a) and clinical isolate M38100B4 (b), respectively, as described in Materials and Methods. The clinical isolate M38100B4 carries an amino acid substitution (M292T) in PmrB causing polymyxin B resistance (MIC 8 μg/mL) as reported (1). Error bars were obtained from three independent assays. (a) Diamond, a strain PAO1; triangle, a strain PAO1 (phoQ::Gm/ΔpmrAB::Tc)/pAU129 (pmrAB carrying M292T in PmrB); square, a strain PAO1 (phoQ::Gm/ΔpmrAB::Tc) /pAU126 (intact pmrAB from PAO1); (b) Triangle, a strain M38100B4; squares, a strain M38100B4 carrying inactivated-PhoQ. The clones of pAU126 and pAU129 were used from the previous reports (1).