TABLE 3.
MICs of FOX, CTX, and CAZ in E. coli wild-type BW25113 and in two derivative isogenic Keio mutants carrying a CTX-M-1-encoding plasmid (ΔdapF and ΔmrcB)
| Cephem | MICa (μg/ml) |
||||
|---|---|---|---|---|---|
| Wild type | ΔmrcB | ΔdapF | Susceptibility breakpoint | Resistance breakpoint | |
| FOX | 4 | 0.5 | 0.5 | ≤8 | ≥ 32 |
| CTX | 16 | 2 | 1 | ≤1 | ≥ 4 |
| CAZ | 2 | 0.25 | 0.25 | ≤4 | ≥ 16 |
a
MICs below the CLSI susceptibility breakpoints for Enterobacteriaceae (37) are indicated in boldface. The MICs of drugs for which individual gene deletion resulted in a synergistic effect (interaction index ≤ 0.25) are underlined.