Table 2.
Minimum inhibitory concentrations (MICs) of mcr-1-positive E. coli strains and their transconjugants.
| Strain | Origin a | mcr-1 Gene b | MIC c (μg/mL) | |||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|
| AMP | CEF | TET | CHL | CIP | KAN | GEN | STR | POL | COL | |||
| E. coli JSMCR1 | WT | + | >64 | >64 | 128 | >64 | >8 | >32 | >64 | 64 | 8 | 8 |
| E. coli FORC81 | WT | + | >64 | 64 | >128 | >64 | >8 | 8 | >64 | 8 | 8 | 8 |
| E. coli FORC82 | WT | + | >64 | >64 | 128 | 64 | 2 | 4 | 2 | 2 | 8 | 8 |
| EHEC (E. coli ATCC 43889) | WT | - | ≤0.5 | ≤0.5 | ≤0.0628 | ≤0.5 | ≤0.0039 | ≤0.25 | ≤0.5 | >128 | ≤0.25 | ≤0.25 |
| pJSMCR1/EHEC | TC | + | ≤0.5 | ≤0.5 | ≤0.0628 | ≤0.5 | ≤0.0039 | ≤0.25 | ≤0.5 | >128 | 4 | 4 |
| pFORC81/EHEC | TC | + | ≤0.5 | ≤0.5 | ≤0.0628 | ≤0.5 | ≤0.0039 | ≤0.25 | ≤0.5 | >128 | 4 | 4 |
| pFORC82/EHEC | TC | + | ≤0.5 | ≤0.5 | ≤0.0628 | ≤0.5 | ≤0.0039 | ≤0.25 | ≤0.5 | >128 | 4 | 4 |
| ETEC (isolate) | WT | - | >64 | 8 | 32 | 64 | 0.0312 | >32 | >64 | >128 | 4 | 2 |
| pJSMCR1/ETEC | TC | + | >64 | 8 | 32 | 64 | 0.0312 | >32 | >64 | >128 | 8 | 8 |
| pFORC81/ETEC | TC | + | >64 | 8 | 32 | 64 | 0.0312 | >32 | >64 | >128 | 8 | 8 |
| pFORC82/ETEC | TC | + | >64 | 8 | 32 | 64 | 0.0312 | >32 | >64 | >128 | 8 | 8 |
| EAEC (E. coli NCCP 14039) | WT | - | >64 | 16 | >128 | 4 | 0.0312 | 8 | 2 | >128 | 4 | 2 |
| pJSMCR1/EAEC | TC | + | >64 | 16 | >128 | 4 | 0.0312 | 8 | 2 | >128 | 8 | 4 |
| pFORC81/EAEC | TC | + | >64 | 16 | >128 | 4 | 0.0312 | 8 | 2 | >128 | 8 | 8 |
| pFORC82/EAEC | TC | + | >64 | 16 | >128 | 4 | 0.0312 | 8 | 2 | >128 | 8 | 8 |
| S. Typhimurium SL1344 | WT | - | 2 | 2 | 0.5 | 4 | 0.0156 | 4 | 2 | >128 | 4 | 4 |
| pJSMCR1/SL1344 | TC | + | 2 | 2 | 0.5 | 4 | 0.0156 | 4 | 2 | >128 | 8 | 8 |
| pFORC81/SL1344 | TC | + | 2 | 2 | 0.5 | 4 | 0.0156 | 4 | 2 | >128 | 8 | 8 |
| pFORC82/SL1344 | TC | + | 2 | 2 | 0.5 | 4 | 0.0156 | 4 | 2 | >128 | 8 | 8 |
| Klebsiella (isolate) | WT | - | >64 | 16 | >128 | >64 | >16 | >32 | 1 | >128 | 4 | 4 |
| pJSMCR1/Klebsiella | TC | + | >64 | 16 | >128 | >64 | >16 | >32 | 1 | >128 | 8 | 16 |
| pFORC81/Klebsiella | TC | + | >64 | 16 | >128 | >64 | >16 | >32 | 1 | >128 | 8 | 16 |
| pFORC82/Klebsiella | TC | + | >64 | 16 | >128 | >64 | >16 | >32 | 1 | >128 | 32 | 16 |
a WT: wild type, TC: Transconjugant. b Presence (+) or absence (-) of mcr-1, based on PCR and confirmed by sequencing. c AMP: ampicillin, CEF: cephalothin, TET: tetracycline, CHL: chloramphenicol, CIP: ciprofloxacin, KAN: Kanamycin; GEN: gentamicin; STR: streptomycin; POL: polymyxin B; COL: colistin.