TABLE 5.
Effect of alternative sigma factor sigB on the emergence of glycopeptide resistance
| Strain | Description | Relevant genotype | CFU Σtot (n) | FOEa (T2/T0) | MIC (μg/ml)b |
|
|---|---|---|---|---|---|---|
| Teicoplanin | Vancomycin | |||||
| ISP794 | ΔrsbU | 1,065 (3) | 1.1 × 10−6 | 1-2 | 1-2 | |
| AR850 | ISP794, ΔsigB operon | ΔrsbUVW sigB::ermB | 280 (3) | 3.5 × 10−7 | 2 | 1 |
| AR851 | ISP794, ΔsigB | sigB::Tn551 | 633 (3) | 8.0 × 10−7 | 1 | 1 |
| AR852 | ISP794, rsbU+ | (rsbUVW-sigB)+, tetL nearby | >3,000 (3)c | >3.0 × 10−5d | 2 | 2 |
a
The frequency of emergence (FOE) was determined as described in Table 4, footnote a.
b
Defined in Table 3, footnote a.
c
Viable counts on agar containing 2 μg of teicoplanin/ml were too high to accurately measure using these conditions compared to ISP794. More than 1,000 CFU were estimated in each experiment.
d
The value reported is an estimate of the lower limit using CFU data obtained under identical conditions for the frequency determined with ISP794.