MIC determination of Az for F. novicida transposon LPS and RND efflux mutants and F. tularensis Schu S4 RND efflux mutants. A) The MIC of Az for LPS O-antigen F. novicida transposon mutants was generally higher than the wild-type (circle) MIC of 0.78 μg/ml. MICs for LPS O-antigen mutants were 12.5 μg/ml for wbtA (diamond), 25.0 μg/ml for wbtE (down triangle), 3.12 μg/ml for wbtQ (square), and 12.5 μg/ml for wbtN (triangle), with an EC50 for all LPS O-antigen mutants greater than 0.50 μg/ml (p-value < 0.005). B) MICs for F. novicida transposon-insertion RND efflux mutant varied: dsbB (down triangle) was closer to the wild-type (closed circle) at 1.56 μg/ml (p-value 0.400). ftlC, tolC, acrA, and acrB have greater MIC with 25 μg/ml for ftlC (square) and 50 μg/ml for tolC (up triangle), acrA (diamond), and acrB (open circle), with EC50 greater than 12 μg/ml (p-value < 0.005). C) The MICs of Az for F. tularensis Schu S4 (square) and deletion RND efflux mutants. F. tularensis Schu S4 (square) has an MIC of 0.78 μg/ml, ΔacrB (circle) of 1.56 μg/ml, and ΔacrA (diamond) of 3.13 μg/ml. F. tularensis Schu S4 and mutants all have EC50 less than 0.15 μg/ml (p-value < 0.1 for ΔacrA and ΔacrB compared to wild-type).