TABLE 3.
MICs of cephalosporins against selected MSSA and MRSA strains at pH 7.4 and 5.5 in broth and pH-induced decreases in MICs
| Cephalosporin | MSSA ATCC 25923
|
MRSA ATCC 33591
|
Decrease in MRSA MIC/MSSA MIC ratio | MRSA MIC/MSSA MIC ratio at pH 5.5 | ||||
|---|---|---|---|---|---|---|---|---|
| MIC (mg/liter)
|
pH-induced MIC decrease (fold) | MIC (mg/liter)
|
pH-induced MIC decrease (fold) | |||||
| pH 7.4 | pH 5.5 | pH 7.4 | pH 5.5 | |||||
| Cephalexin | 2 | 1 | 2 | 256 | 16 | 16 | 8 | 16 |
| Cefuroxime | 2 | 0.125 | 16 | 128 | 1 | 128 | 8 | 4 |
| Cefoxitin | 1 | 0.25 | 4 | 512 | 1 | 512 | 128 | 4 |
| Ceftriaxone | 2 | 0.125 | 16 | 512 | 1 | 512 | 32 | 4 |
| Ceftobiprole | 0.5 | 0.25 | 2 | 2 | 0.5 | 4 | 2 | 2 |