TABLE 3.
In vitro activities of quinupristin-dalfopristin and seven other antibiotics against S. haemolyticus strains (n = 50) isolated from patients with bloodstream infections in Germanya
| Antibiotic | No. of strains for which MIC (mg/liter) is:
|
MIC90 (mg/liter) | Susceptibilityb
|
|||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| ≤0.06 | 0.125 | 0.25 | 0.5 | 1 | 2 | 4 | 8 | 16 | 32 | ≥64 | % S | % R | ||
| Penicillin G | 1 | 0 | 0 | 1 | 1 | 1 | 1 | 3 | 42 | — | — | 16 | 2.0 | 98.0 |
| Oxacillin | 4 | 0 | 0 | 0 | 1 | 0 | 1 | 1 | 43 | — | — | ≥16 | 10.0 | 90.0 |
| Erythromycin | — | — | 2 | 5 | 0 | 0 | 1 | 0 | 2 | 9 | 31 | ≥64 | 14.0 | 84.0 |
| Clindamycin | — | — | 27 | 0 | 0 | 2 | 1 | 1 | 0 | 0 | 19 | ≥64 | 54.0 | 40.0 |
| Ciprofloxacin | 0 | 0 | 0 | 2 | 0 | 0 | 0 | 1 | 47 | — | — | ≥16 | 4.0 | 96.0 |
| Gentamicin | — | — | 4 | 0 | 0 | 0 | 1 | 3 | 42 | — | — | ≥16 | 8.0 | 90.0 |
| Teicoplanin | — | — | 2 | 3 | 3 | 10 | 17 | 10 | 5 | 0 | 0 | 8 | 70.0 | 10.0 |
| Vancomycin | — | — | 0 | 5 | 24 | 16 | 5 | 0 | 0 | 0 | 0 | 2 | 100 | 0 |
| Q-D | — | — | 36 | 12 | 1 | 1 | 0 | 0 | 0 | 0 | 0 | 0.5 | 98.0 | 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).