Table 2.

Antimicrobial susceptibility profiles of E. coli strains used in conjugation and expression experimentsa

StrainDesignationMIC (μg/ml)
AmoAmpCefCetCepFoxCmlKanNalStrSulTet
CVM1320Donor>32>32816>32>32≤4≤16≤4128≤128>32
CVM990Recipient44≤0.5≤0.258≤4≤4>64≤4>256>512>32
1320/990Transconjugant>32>32>1664>32>328>64≤4>256>512>32
JM263Recipient881≤0.25323232≤16>256≤32≤1288
1320/263Transconjugant>32>32>1664>3232≤16>256≤32≤1288
BL21(DE3)pLysSHost cell2≤2≤0.5≤0.252≤4>32≤16≤4≤32≤128≤4
BL21(DE3)pLysS + pET34bHost cell + vector2≤2≤0.5≤0.252≤4>32>64≤4≤32≤128≤4
BL21 (DE3)pLysS + pET34b-cmyTransformant>32>3284>3216>32>64≤4≤32≤128≤4
  • a Amo, amoxicillin-clavulanic acid; Amp, ampicillin; Cef, ceftiofur; Cet, ceftriaxone; Cep, cephalothin; Fox, cefoxitin; Cml, chloramphenicol; Kan, kanamycin; Nal, nalidixic acid; Str, streptomycin; Sul, sulfamethoxazole; Tet, tetracycline. All isolates were susceptible to amikacin, apramycin, ciprofloxacin, gentamicin, and trimethoprim-sulfamethoxazole. β-Lactam antimicrobials are bolded and italicized. MICs were determined via broth microdilution methods in accordance with NCCLS guidelines (12, 13). Resistance is indicated by boldface values.