Table 2.
Molecular mechanisms of rifaximin resistancea
| Diagnosis | Patient ID | E. coli strain ID | Rifx treatment |
Strain type | MIC Rifx (mg/liter) | MIC Rifx + PAβN (mg/liter) | Mutations in rpoB |
||
|---|---|---|---|---|---|---|---|---|---|
| Duration (mo) | Time between last Rifx dose and ileal biopsy (days) | Codon | Amino acid substitution | ||||||
| CD (L2) | 524 | 524-2 | 2.6 | 27 | R | >1,024 | 128 | 526 | H→N |
| 14 | 14GK-1 | 24.5 | 0 | R | >1,024 | 64 | 526 | H→N | |
| CD (L1+L3) | 75 | 75TI-1 | 5 | 6 | R | >1,024 | 8 | 518 | N→D |
| 552 | 552-P4 | 5 | 0 | R | >1,024 | 8 | None | None | |
| 552 | 552-2 | 5 | 0 | R | >1,024 | 8 | None | None | |
| 24 | 24LW-1 | 16 | 0 | R | >1,024 | >1,024 | 516 | D→N | |
| 32 | 32SY-1 | 26 | 0 | R | >1,024 | 32 | 574 | S→F | |
| 578 | 578-1 | 0.6 | 0 | R | >1,024 | 128 | 516 | D→N | |
| UC | 40 | 40EM-1 | 0.4 | 0 | R | >1,024 | >1,024 | 526 | H→L |
| 48 | 48JD-1 | Unknown | 0 | R | >1,024 | 32 | 526 | H→N | |
| 58 | 58PP-1 | 7 | 0 | R | >1,024 | >1,024 | 513, 574 | Q→H, S→F | |
| 60 | 60CM-1 | 13 | 131 | R | >1,024 | 8 | 574 | S→Y | |
| CD (L1+L3) | 541 | 541-1 | NT | NT | S | 32 | 8 | None | None |
| 541 | 541-15 | NT | NT | S | 32 | 8 | None | None | |
| 41 | 41CB-1 | NT | NT | S | 16 | 8 | None | None | |
a
Rifx, rifaximin; NT, no rifaximin treatment; R, resistant; S, sensitive; rifaximin resistant, MIC > 32 mg/liter; rifaximin sensitive, MIC ≤ 32 mg/liter.