Table 2.
EP gene expression analysis by RT-qPCR of representative S. aureus exposed to CIP or EtBr.
| Overexpression levels* and no. of isolates** showing gene overexpression | ||||||
|---|---|---|---|---|---|---|
| ½ CIP MIC | ½ EtBr MIC | |||||
| EtBrCW- | EtBrCW+ | EtBrCW- | EtBrCW+ | |||
| Gene | ATCC25923 | isolates | isolates | ATCC25923 | isolates | isolates |
| (n = 4) | (n = 6) | (n = 4) | (n = 6) | |||
| norA | - | - | - | 4.51 ± 0.77 | - | - |
| 0 | 0 | 0 | 0 | |||
| norB | 13.80 ± 6.50 | 5.43 ± 2.39 | 5.47 ± 0.19 | 7.07 ± 2.78 | 5.33 ± 0.73 | - |
| 2a, b | 1e | 1a | 0 | |||
| norC | - | - | 4.92 ± 0.00 | 5.89 ± 0.71 | 4.99 ± 1.51 | - |
| 0 | 1e | 1a | 0 | |||
| mepA | - | - | 8.59 ± 0.59 | 3.90 ± 0.13 | 5.94 ± 1.02 | - |
| 0 | 1f | 1a | 0 | |||
| mdeA | - | 4.97 ± 0.68 | - | 3.96 ± 2.10 | - | 4.15 ± 1.12 |
| 1c | 0 | 0 | 1d | |||
| smr | n.a. | n.a. | - | n.a. | n.a. | 7.66 ± 3.66 |
| 0 | 1f | |||||
* Gene expression was measured in the presence of ciprofloxacin and EtBr relatively to the drug-free condition. The results are expressed in terms of the mean ± standard deviation of at least three independent assays performed with independently extracted RNAs and correspond to the range of values obtained for isolates showing overexpression of that gene. **The numbers in bold correspond to the number of isolates overexpressing that gene: a isolate SM2; b SM3; c SM5; dSM25; e SM50; f SM52. Overexpression was considered for values ≥4 [10]. (-): no overexpression was detected; n.a.: not applicable.