Table 3.
Minimal inhibitory concentrations of the 59 canine and feline E. coli isolates.
| Antimicrobial Agent (s) | Number of Isolates for Which the MIC Value (mg/L) Is | |||||||||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| 0.008 | 0.015 | 0.03 | 0.06 | 0.12 | 0.25 | 0.5 | 1 | 2 | 4 | 8 | 16 | 32 | 64 | 128 | 256 | 512 | 1024 | |
| Penicillin G | - | - | - | - | - | - | - | - | - | 1 | - | 12 | 46 | |||||
| Ampicillin | - | - | - | - | 1 | - | 4 | 6 | - | - | - | - | 31 | |||||
| Ampicillin (UTI) | - | - | - | - | - | - | 7 | 4 | - | - | - | - | 6 | |||||
| Amoxicillin-clavulanic acid (2:1) | - | - | - | - | - | 1 | 3 | 8 | 8 | 14 | 3 | 4 | 1 | |||||
| Amoxicillin-clavulanic acid (2:1) (UTI) | - | - | - | - | - | - | 2 | 8 | 3 | 2 | 2 | - | - | |||||
| Imipenem | - | - | - | 39 | 18 | 1 | - | - | 1 | - | - | - | - | |||||
| Cephalothin | - | - | - | - | 1 | - | - | 8 | 17 | 8 | 2 | - | 23 | |||||
| Cefotaxime | - | 1 | 17 | 14 | 2 | 1 | - | - | 1 | 1 | 2 | 2 | 18 | |||||
| Cefoperazone | 1 | 4 | 12 | 6 | 1 | 2 | 4 | 2 | 1 | 3 | 23 | |||||||
| Ceftiofur | - | - | 2 | 8 | 23 | 2 | 1 | - | - | 4 | - | - | 19 | |||||
| Florfenicol | - | - | - | - | - | 10 | 35 | 10 | 1 | 1 | - | 1 | 1 | |||||
| Streptomycin | - | - | - | - | 13 | 16 | 3 | 2 | - | 6 | 7 | 3 | 9 | |||||
| Gentamicin | - | 1 | 29 | 15 | 3 | - | - | 1 | 5 | 4 | 1 | - | - | |||||
| Neomycin | - | 1 | 18 | 26 | 4 | 1 | 1 | - | 1 | 2 | 5 | |||||||
| Ciprofloxacin | 1 | 17 | 11 | 2 | 2 | 1 | 2 | - | - | - | 4 | 4 | 15 | |||||
| Enrofloxacin | - | 6 | 20 | 5 | 1 | 1 | 2 | 1 | 1 | - | - | 5 | 17 | |||||
| Marbofloxacin | - | 5 | 21 | 5 | 2 | - | 1 | 2 | - | - | 7 | 12 | 4 | |||||
| Nalidixic acid | - | - | - | - | 4 | 23 | 3 | 2 | - | 3 | - | 1 | 23 | |||||
| Trimethoprim-sulfamethoxazole (1:19) | - | 1 | 19 | 9 | 2 | 2 | 2 | - | - | - | - | 1 | 23 | |||||
| Tetracycline | - | - | - | 11 | 16 | 7 | - | - | - | 6 | 14 | 5 | - | |||||
| Doxycycline | - | - | - | 2 | 14 | 13 | 3 | 6 | 6 | 10 | 4 | 1 | - | |||||
| Colistin | 1 | - | - | 6 | 51 | - | 1 | - | - | - | - | - | - | |||||
The black areas are the test ranges not included in the test panels for the respective antimicrobial agents. Isolates that had no growth in any of the concentrations were given the lowest MIC value. Isolates with growth in all tested concentrations were given the next serially higher MIC value above the highest tested concentration (white number on black background). The MIC values of amoxicillin-clavulanic acid (2:1) and trimethoprim-sulfamethoxazole (1:19) are expressed as the MIC values of amoxicillin and trimethoprim, respectively. Different gray shading indicates the categories: susceptible—light gray; intermediate—middle gray; resistant—dark gray. For the clinical breakpoints used, please see Materials and Methods, Section 4.2.