Table 1.
Antimicrobial susceptibilities of the E. coli O145 outbreak isolate and transformant
| Antimicrobial agent | MIC (μg/ml) fora: |
|
|---|---|---|
| Original isolate | Transformant | |
| Amikacin | 2 | 1 |
| Amoxicillin-clavulanic acid | ≤1 | 4 |
| Ampicillin | 2 | 4 |
| Cefoxitin | 8 | 4 |
| Ceftiofur | 0.5 | 0.5 |
| Ceftriaxone | ≤0.25 | ≤0.25 |
| Chloramphenicol | >32 | >32 |
| Ciprofloxacin | 0.25 | ≤0.015 |
| Gentamicin | 0.5 | ≤0.25 |
| Kanamycin | ≤8 | ≤8 |
| Nalidixic acid | >32 | 1 |
| Streptomycin | >64 | >64b |
| Sulfisoxazole | >256 | >256 |
| Tetracycline | >32 | 32 |
| Trimethoprim-sulfamethoxazole | 0.25 | ≤0.12 |
a
One representative isolate and transformant are shown. MICs in bold are considered resistant as defined by CLSI interpretive standards, when available (8). For ceftiofur and streptomycin, the resistance breakpoints used are 8 and 64 μg/ml, respectively (6).
b
The DH10B cell line is streptomycin resistant (rpsL) prior to transformation, but the transfer of strA and strB was confirmed by PCR analysis.