To test the ability of RBFE to predict antibiotic resistance we selected a small number of mutations in the RNAP and DNAG that confer resistance; to act as negative controls we added several more mutations known to have no clinical effect. We chose to test the most common resistanceconferring mutations for each drug. For RNAP this is S450L in the RRDR of rpoB and for the DNA gyrase these are A90V and D94G in the QRDR of gyrA (Fig. ). D94G is a robust test of RBFE as the mutation involves a significant change in amino acid properties and electrical charge.