Table 3.
Antibiotics | MIC (mg/L) of β-lactam antibiotics | ||||||||||
---|---|---|---|---|---|---|---|---|---|---|---|
Concentration of C a + ECg b (mg/L) | |||||||||||
| |||||||||||
0 | 16 + 2 | 32 + 4 | |||||||||
|
|
|
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Range | MIC50 | MIC90 | Range | MIC50 | MIC90 | FICI c | Range | MIC50 | MIC90 | FICI c | |
oxacillin | 128–512 | 256 | 512 | 4–512 | 128 | 256 | 0.56 ± 0.32 (13/45) | 4–256 | 32 | 256 | 0.31 ± 0.22 (36/45) |
ampicillin | 32–512 | 64 | 128 | 2–256 | 16 | 64 | 0.37 ± 0.26 (30/45) | 2–256 | 8 | 32 | 0.29 ± 0.24 (39/45) |
ampicillin/sulbactam | 8–32 | 32 | 32 | 2–32 | 16 | 32 | 0.58 ± 0.29 (14/45) | 2–16 | 8 | 16 | 0.39 ± 0.23 (33/45) |
cefazolin | 4–512 | 256 | 512 | 4–512 | 128 | 256 | 0.47 ± 0.33 (20/45) | 4–256 | 32 | 128 | 0.25 ± 0.18 (39/45) |
cefepime | 8–2048 | 1024 | 1024 | 8–1024 | 256 | 512 | 0.45 ± 0.23 (18/45) | 8–1024 | 128 | 512 | 0.30 ± 0.20 (39/45) |
imipenem/cilastatin | 4–512 | 128 | 256 | 4–512 | 32 | 64 | 0.36 ± 0.25 (29/45) | 4–512 | 4 | 32 | 0.23 ± 0.25 (41/45) |
| |||||||||||
Antibiotics | MIC (mg/L) of β-lactam antibiotics | ||||||||||
Concentration of Ca+ ECgb(mg/L) | |||||||||||
| |||||||||||
64 + 8 | 128 + 16 | ||||||||||
|
|
||||||||||
Range | MIC50 | MIC90 | FICIc | Range | MIC50 | MIC90 | FICIc | ||||
| |||||||||||
oxacillin | 4–256 | 4 | 128 | 0.28 ± 0.19 (42/45) | 4–256 | 4 | 4 | 0.41 ± 0.22 (31/45) | |||
ampicillin | 2–256 | 2 | 16 | 0.27 ± 0.19 (42/45) | 2–256 | 2 | 2 | 0.29 ± 0.22 (31/45) | |||
ampicillin/sulbactam | 2–16 | 2 | 4 | 0.30 ± 0.19 (42/45) | 2–16 | 2 | 2 | 0.44 ± 0.12 (33/45) | |||
cefazolin | 4–64 | 4 | 32 | 0.23 ± 0.15 (44/45) | 4–4 | 4 | 4 | 0.39 ± 0.21 (32/45) | |||
cefepime | 8–256 | 8 | 64 | 0.25 ± 0.17 (44/45) | 8–16 | 8 | 8 | 0.39 ± 0.23 (32/45) | |||
imipenem/cilastatin | 4–512 | 4 | 4 | 0.28 ± 0.30 (42/45) | 4–512 | 4 | 4 | 0.45 ± 0.26 (32/45) |
For C, the MIC range, MIC50, MIC90 against 45 MRSA clinical strains were 512–4096 mg/L, 2048 mg/L and 4096 mg/L, respectively;
For ECg, the MIC range, MIC50, MIC90 against 45 MRSA clinical strains were 32–1024 mg/L, 64 mg/L and 1024 mg/L, respectively;
Data are expressed as means ± standard deviations. Values in parentheses represent the number of strains for which drug combinations resulted in synergism/number of strains tested.