78 μg/ml) (p-value < 0.005) (Figure 4A, Table 5), suggesting increased resistance to Az. Selleck Baf-A1 These data are consistent with the disc inhibition studies, suggesting that Francisella LPS plays some role in the sensitivity

of the Selleckchem VX-680 strains for Az. Table 4 Az Disk Inhibition Assay with Francisella transposon mutants of LPS production genes.   Antibiotic No Growth Zone (mm) F. novicida Avg P-value wild-type 28.7 ± 0.7 ——- wbtA 20.8 ± 0.5 <0.001 wbtN 23.3 ± 0 <0.001 wbtE 23.0 ± 0.9 <0.001 wbtQ 20.1 ± 1.3 <0.001 15 ug Az discs from Fluka were placed on an agar plate spread with the indicated strain. The zone of inhibition was measured in mm. Table 5 MIC Assay of Az for F. novicida transposon mutants. Bacteria AZ MIC (μg/ml) AZ EC50(μg/ml) p-value F. novicida 0.78 0.16 ------ wbtQ 3.12 0.52 0.005 wbtN 12.5 0.54 <0.002 wbtE 25 0.50 <0.001 wbtA 12.5 0.67 0.007 dsbB 1.56 0.16 0.401 ftlC 25 13.47 <0.002 tolC 50 16.44 <0.001 acrA 50 12.39 <0.001 acrB 50 13.23 0.001 F. tularensis Schu S4 0.78 0.1453 ------- ΔacrA 3.13 0.0852 0.087 ΔacrB 1.56 0.0493 0.031 MIC and EC50 were calculated as described. p-values compare the EC50 of mutants to wild-type SBE-��-CD supplier F. novicida and F. tularensis Schu S4. Figure 4 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 medroxyprogesterone 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). Francisella RND mutants Five F. novicida transposon insertion mutants in the multidrug efflux protein genes (acrA and acrB), the transcriptionally linked protein gene (dsbB), as well as the related outer membrane channel genes (tolC and ftlC) were tested to determine if Az susceptibility increases or decreases [12].