TABLE 4.
In vitro activities of quinupristin-dalfopristin and seven other antibiotics against oxacillin-resistant strains of S. aureus, S. epidermidis, and S. haemolyticus isolated from patients with bloodstream infectionsa
| Species | Antibiotic | No. of strains for which MIC (mg/liter) is:
|
MIC90 (mg/liter) | Susceptibilityb
|
||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| ≤0.125 | 0.25 | 0.5 | 1 | 2 | 4 | 8 | 16 | 32 | ≥64 | % S | % R | |||
| S. aureus | Erythromycin | — | 25 | 29 | 11 | 4 | 4 | 1 | 2 | 4 | 115 | ≥64 | 33.3 | 62.6 |
| (n = 195) | Clindamycin | — | 89 | 0 | 1 | 3 | 0 | 0 | 0 | 2 | 100 | ≥64 | 46.2 | 52.3 |
| Ciprofloxacin | 2 | 19 | 32 | 15 | 5 | 4 | 12 | 106 | — | — | 16 | 34.9 | 62.6 | |
| Gentamicin | — | 5 | 20 | 32 | 21 | 4 | 4 | 109 | — | — | 16 | 29.2 | 57.9 | |
| Teicoplanin | — | 20 | 46 | 70 | 55 | 4 | 0 | 0 | 0 | — | 2 | 100 | 0.0 | |
| Vancomycin | — | 5 | 44 | 121 | 23 | 2 | 0 | 0 | 0 | — | 2 | 100 | 0.0 | |
| Q-D | — | 81 | 82 | 26 | 6 | 0 | 0 | 0 | 0 | — | 1 | 97.0 | 0.0 | |
| S. epidermidis | Erythromycin | — | 43 | 21 | 8 | 2 | 0 | 0 | 1 | 4 | 237 | ≥64 | 22.8 | 76.6 |
| (n = 316) | Clindamycin | — | 139 | 3 | 3 | 0 | 0 | 1 | 0 | 4 | 166 | ≥64 | 45.9 | 54.1 |
| Ciprofloxacin | 6 | 22 | 42 | 13 | 3 | 23 | 47 | 160 | — | — | 16 | 26.3 | 72.8 | |
| Gentamicin | — | 63 | 3 | 2 | 2 | 3 | 20 | 223 | — | — | 16 | 21.2 | 76.9 | |
| Teicoplanin | — | 11 | 7 | 38 | 87 | 116 | 52 | 4 | 0 | 1 | 8 | 82.0 | 1.6 | |
| Vancomycin | — | 0 | 15 | 141 | 154 | 6 | 0 | 0 | 0 | — | 2 | 100 | 0.0 | |
| Q-D | — | 298 | 9 | 6 | 3 | 0 | 0 | 0 | 0 | — | 0.25 | 99.0 | 0.0 | |
| S. haemolyticus | Erythromycin | — | 1 | 4 | 0 | 0 | 1 | 0 | 2 | 9 | 28 | ≥64 | 11.1 | 86.7 |
| (n = 45) | Clindamycin | — | 23 | 0 | 0 | 2 | 1 | 1 | 0 | 0 | 18 | ≥64 | 51.1 | 42.2 |
| Ciprofloxacin | 0 | 0 | 0 | 0 | 0 | 0 | 1 | 44 | — | — | 16 | 0.0 | 100 | |
| Gentamicin | — | 0 | 0 | 0 | 0 | 1 | 3 | 41 | — | — | ≥16 | 0.0 | 97.8 | |
| Teicoplanin | — | 0 | 2 | 3 | 10 | 16 | 9 | 5 | 0 | — | 16 | 68.9 | 11.1 | |
| Vancomycin | — | 0 | 2 | 23 | 15 | 5 | 0 | 0 | 0 | — | 2 | 100 | 0.0 | |
| Q-D | — | 32 | 11 | 1 | 1 | 0 | 0 | 0 | 0 | — | 0.5 | 97.8 | 0.0 | |
Q-D, quinupristin-dalfopristin; S, susceptible; R, resistant; —, concentration not tested.
The following breakpoints were used for definition of susceptibility (resistance); penicillin, ≤0.125 mg/liter (≥0.25 mg/liter) (DIN); oxacillin, ≤1 mg/liter (≥2 mg/liter) (DIN); erythromycin, ≤1 mg/liter (≥8 mg/liter) (DIN); clindamycin, ≤1 mg/liter (≥8 mg/liter) (DIN); ciprofloxacin, ≤1 mg/liter (≤4 mg/liter) (DIN); gentamicin, ≤1 mg/liter (≥8 mg/liter) (DIN); teicoplanin, ≤1 mg/liter (≥16 mg/liter) (tentative breakpoint); vancomycin, ≤4 mg/liter (≥16 mg/liter) (DIN); quinupristin-dalfopristin, ≤1 mg/liter (≥4 mg/liter) (tentative breakpoint).