TABLE 2.
Antimicrobial susceptibilities with MICs of AMR environmental Salmonella isolates and corresponding E. coli transconjugants
| Salmonella isolate or transconjuganta | MIC (μg/ml)b |
|||||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| AMP | AUG2 | AXO | AZI | CHL | CIP | FIS | FOX | GEN | NAL | STR | SXT | XNL | TET | |
| S6 | <1 | <1/0.5 | <0.25 | 4 | 8 | <0.015 | >256 | 4 | 16 | 2 | 64 | <0.12/2.38 | 1 | >32 |
| TC-S6 | <1 | 2/1 | <0.25 | 2 | 8 | 0.06 | >256 | 4 | 16 | >32 | 64 | <0.12/2.38 | 0.5 | >32 |
| S7 | <1 | <1/0.5 | <0.25 | 4 | 8 | <0.015 | >256 | 4 | 16 | 2 | >64 | <0.12/2.38 | 0.5 | >32 |
| TC-S7 | 2 | 2/1 | <0.25 | 2 | 8 | 0.12 | >256 | 4 | 8 | >32 | 64 | <0.12/2.38 | 0.5 | >32 |
| S8 | <1 | <1/0.5 | <0.25 | 4 | 8 | <0.015 | >256 | 4 | >16 | 2 | 64 | <0.12/2.38 | 0.5 | >32 |
| TC-S8 | 2 | 2/1 | <0.25 | 2 | 8 | 0.12 | >256 | 2 | 8 | >32 | 64 | <0.12/2.38 | 0.5 | >32 |
| S9 | >32 | 32/16 | 16 | 8 | 8 | 0.03 | 256 | 32 | 0.5 | 4 | 4 | <0.12/2.38 | >8 | <4 |
| TC-S9 | >32 | 32/16 | 16 | 2 | 8 | 0.12 | <16 | 32 | <0.25 | >32 | 4 | <0.12/2.38 | 4 | <4 |
| S10 | >32 | 32/16 | 16 | 8 | 8 | 0.03 | 256 | 32 | 0.5 | 4 | 8 | <0.12/2.38 | >8 | <4 |
| TC-S10 | >32 | 32/16 | 16 | 2 | 8 | 0.25 | <16 | >32 | 0.5 | >32 | 4 | <0.12/2.38 | 4 | <4 |
| S12 | >32 | 8/4 | <0.25 | 4 | 8 | <0.015 | >256 | 2 | 0.5 | 4 | 8 | <0.12/2.38 | 0.5 | <4 |
| TC-S12 | >32 | 8/4 | <0.25 | 4 | 8 | 0.12 | >256 | 4 | 0.5 | >32 | 8 | <0.12/2.38 | 1 | <4 |
| S13 | >32 | 8/4 | <0.25 | 4 | 8 | <0.015 | >256 | 2 | 0.5 | 4 | 8 | 0.25/4.75 | 0.5 | <4 |
| TC-S13 | >32 | 8/4 | <0.25 | 4 | 8 | 0.12 | >256 | 4 | 0.5 | >32 | 8 | <0.12/2.38 | 1 | <4 |
| S14 | >32 | 8/4 | <0.25 | 4 | 8 | <0.015 | >256 | 2 | 0.5 | 4 | 8 | <0.12/2.38 | 1 | <4 |
| TC-S14 | >32 | 8/4 | <0.25 | 4 | 8 | 0.12 | >256 | 2 | 0.5 | >32 | 8 | <0.12/2.38 | 1 | <4 |
| S15 | >32 | <1/0.5 | <0.25 | 4 | 8 | 0.25 | >256 | 2 | 0.5 | 4 | 8 | <0.12/2.38 | 1 | <4 |
| TC-S15 | >32 | 8/4 | <0.25 | 4 | 8 | 0.25 | >256 | 2 | 0.5 | >32 | 16 | 0.25/4.75 | 1 | <4 |
| S20 | <1 | <1/0.5 | <0.25 | 8 | 8 | 0.03 | 64 | 4 | 0.5 | 4 | 4 | <0.12/2.38 | 1 | >32 |
| TC-S20 | 2 | 2/1 | <0.25 | 4 | 8 | 0.12 | <16 | 4 | <0.25 | >32 | 4 | <0.12/2.38 | <0.12 | >32 |
| S24 | >32 | 4/2 | <0.25 | 8 | 8 | 0.03 | >256 | 2 | 0.5 | 8 | >64 | <0.12/2.38 | 1 | >32 |
| TC-S24 | >32 | 8/4 | <0.25 | 4 | 8 | 0.12 | >256 | 2 | 0.5 | >32 | >64 | <0.12/2.38 | 0.5 | >32 |
| S27 | >32 | 32/16 | 8 | 8 | >32 | <0.015 | >256 | 16 | 0.5 | 4 | >64 | <0.12/2.38 | 8 | >32 |
| TC-S27 | >32 | 8/4 | <0.25 | 4 | >32 | 0.12 | >256 | 2 | <0.25 | >32 | 32 | <0.12/2.38 | 0.5 | 32 |
| S28 | <1 | <1/0.5 | <0.25 | 8 | 8 | <0.015 | 64 | 2 | <0.25 | 2 | 4 | <0.12/2.38 | 1 | >32 |
| TC-S28 | 2 | 2/1 | <0.25 | 8 | 8 | 0.12 | <16 | 8 | <0.25 | >32 | 4 | <0.12/2.38 | 0.5 | >32 |
| S29 | <1 | <1/0.5 | <0.25 | 4 | 8 | <0.015 | 64 | 2 | 0.5 | 4 | 8 | <0.12/2.38 | 1 | >32 |
| TC-S29 | 2 | 2/1 | <0.25 | 4 | 8 | 0.12 | <16 | 2 | <0.25 | >32 | <2 | <0.12/2.38 | 0.5 | >32 |
E. coli transconjugants are indicated by designations beginning with “TC.” Salmonella isolate designations begin with the letter “S.”
MIC ranges of the drugs are as follows: amoxicillin-clavulanic acid (AUG2), 1/0.5 to 32/16 μg/ml (breakpoint, ≥32/16 μg/ml); ampicillin (AMP), 1 to 32 μg/ml (breakpoint, ≥32 μg/ml); azithromycin (AZI), 0.12 to 16 μg/ml (breakpoint, ≥32 μg/ml); cefoxitin (FOX), 0.5 to 32 μg/ml (breakpoint, ≥32 μg/ml); ceftiofur (XNL), 0.12 to 8 μg/ml (breakpoint, ≥8 μg/ml); ceftriaxone (AXO), 0.25 to 64 μg/ml (breakpoint, ≥4 μg/ml); chloramphenicol (CHL), 2 to 32 μg/ml (breakpoint, ≥32 μg/ml); ciprofloxacin (CIP), 0.015 ± 4 μg/ml (breakpoint, ≥4 μg/ml); gentamicin (GEN), 0.25 to 16 μg/ml (breakpoint, ≥16 μg/ml); nalidixic acid (NAL), 0.5 to 32 μg/ml (breakpoint, ≥32 μg/ml); streptomycin (STR), 32 to 64 μg/ml (breakpoint, ≥32 μg/ml); sulfisoxazole (FIS), 16 to 256 μg/ml (breakpoint, ≥512 μg/ml); trimethoprim-sulfamethoxazole (SXT), 0.12/2.38 to 4/76 μg/ml (breakpoint, ≥4/76 μg/ml); and tetracycline (TET), 4 to 32 μg/ml (breakpoint, ≥16 μg/ml). Boldface indicates resistance of the Salmonella isolate or transconjugant to the antimicrobial.