Effect of the single point mutations and spx on the emergence of teicoplanin resistance.

1Frequency of emergence expressed as the ratio of colony forming units (CFU) under selective (Teicoplanin 2 µg/ml) and non-selective conditions (No teicoplanin). Colony forming units were counted at 48 h, 37°C.2Viable counts on agar containing 2 µg/ml of teicoplanin were too high to accurately measure using these conditions. More than 1000 CFU were estimated in each experiment.3The effect of rsbU+ on glycopeptide emergence is discussed in Galbusera et al [(30)]. ISP794 emergence frequency was set equal to 100% for normalization and comparison.4The emergence frequency was set equal to 100% for normalization and comparison with its derivative Δspx.