TABLE 1.
Characteristics of Escherichia coli strains and MICs of antibiotics
| E. coli strain (sequence type) | Origin and characteristics | Reference | Antibiotic resistance gene(s)a | MIC (µg/ml) ofb
: |
|||||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| AMP | AZI | CHL | CIP | CST | FOT | GEN | MERO | NAL | SMX | TAZ | TET | TGC | TMP | ||||
| MF2156 (ST3057) | Rectal swab of calf 1, farm 1 | This study | aadA1, aadB, blaTEM-1D, dfrA35, floR, sul1, sul2, tet(A), qacEΔ1 | >64 | ≤2 | 128 | ≤0.015 | ≤1 | ≤0.25 | 8 | ≤0.03 | ≤4 | >1,024 | ≤0.5 | >64 | 0.5 | 256 |
| PF9285 (ST10) | Rectal swab of calf 1, farm 2 | This study | aadA1, aadB, aph(3′)-Ia, blaTEM-1B, catA1, dfrA35, floR, strA, strB, sul1, sul2, tet(A), qacEΔ1 | >64 | 4 | >128 | ≤0.015 | ≤1 | ≤0.25 | 8 | ≤0.03 | ≤4 | >1,024 | ≤0.5 | 32 | ≤0.25 | 256 |
| TOP10 | OneShot TOP10 cells for transformation | Thermo Fisher Scientific | None | 2 | 4 | ≤8 | ≤0.015 | ≤1 | ≤0.25 | ≤0.5 | ≤0.03 | ≤4 | ≤8 | ≤0.5 | ≤2 | ≤0.25 | ≤0.25 |
| TOP10/pT2156c19 | TOP10 with dfrA35 from MF2156 cloned into vector pCR-BluntII-Topo | This study | dfrA35 | 2 | 4 | ≤8 | ≤0.015 | ≤1 | ≤0.25 | ≤0.5 | ≤0.03 | ≤4 | ≤8 | ≤0.5 | ≤2 | ≤0.25 | 128 |
| TOP10/pT9285c17 | TOP10 with dfrA35 from PF9285 cloned into vector pCR-BluntII-Topo | This study | dfrA35 | 2 | 4 | ≤8 | ≤0.015 | ≤1 | ≤0.25 | ≤0.5 | ≤0.03 | ≤4 | ≤8 | ≤0.5 | ≤2 | ≤0.25 | 128 |
Genes and functions: aadA1, streptomycin/spectinomycin adenyltransferase; aadB, gentamicin/tobramycin/kanamycin nucleotidyltransferase; aph(3′)-Ia, kanamycin/neomycin/paromomycin/ribostamycin/lividomycin/gentamicin B phosphotransferase; blaTEM-1B and blaTEM-1D, ampicillin β-lactamase; catA1, chloramphenicol acetyltransferase; dfrA35, trimethoprim dihydrofolate reductase; floR, florfenicol/chloramphenicol exporter; strA, strB, streptomycin phosphotransferase; sul1 and sul2, sulfonamide dihydropteroate synthase; tet(A), tetracycline exporter; qacEΔ1, quaternary ammonium compound multidrug exporter.
Antibiotics: AMP, ampicillin; AZI, azithromycin; CHL, chloramphenicol; CIP, ciprofloxacin; CST, colistin; FOT, cefotaxime; GEN, gentamicin; MERO, meropenem; NAL, nalidixic acid; SMX, sulfamethoxazole; TAZ, ceftazidime; TET, tetracycline; TGC, tigecycline; TMP, trimethoprim. Note that the MICs for TMP have been highlighted in boldface.