Chloroxine

B. thailandensis strain E264 (ATCC; strain 700388) was grown in high salt (10 g/L) Lysogeny broth (LB) at 37°C with aeration at 200 rpm. For experiments investigating the activity of the combination therapy, B. thailandensis was grown to stationary phase in LB broth and cells harvested by centrifugation. Cell pellets were resuspended in M9 minimal media [32 ] supplemented with 730 μM/400 μg/ml ceftazidime hydrate (Melford Laboratories, #C5920; hereafter referred to as ceftazidime). Initial cell counts were determined from the absorbance at 600 nm. An OD₆₀₀ of 0.2 corresponds to 2x10⁸ cfu (Claudia Hemsley, University of Exeter, personal communication). For growth of B. pseudomallei strain K96243 (S. Songsivilai, Siriraj Hospital), bacteria were plated onto low salt (5 g/L) LB-agar. Single colonies were picked into 100 ml low salt LB broth and grown at 37°C for 20 hours with orbital shaking. Cells were harvested by centrifugation and pellets resuspended in M9 minimal media. Ceftazidime was prepared from a stock at 73 mM active component in 0.1 M sodium hydroxide. Chloroxine (Sigma-Aldrich, #D64600) was prepared from a stock at 10–100 mg/ml active component in dimethyl sulfoxide (DMSO).