Table 1.
Synergistic bacteriostatic activities of different antimicrobial combinations against 10 colistin-resistant KPC-producing Klebsiella pneumoniae isolates
| Isolate | ST | ΣFICa ofb: |
|||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|
| CST-RIF | MER-GEN | CST-GEN | CST-MER | CST-IMI | CST-TIG | IMI-GEN | GEN-TIG | MER-TIG | IMI-TIG | ||
| 2018/12 | ST512 | 0.09 | 0.08 | 0.07 | 0.13 | 0.26 | 2.00 | 0.07 | 2.00 | 2.00 | 2.00 |
| 2604/12 | ST512 | 0.38 | 0.38 | 0.07 | 1.13 | 0.25 | 2.00 | 0.38 | 0.56 | 2.00 | 2.00 |
| 2550/12 | ST512 | 0.08 | 0.63 | 0.07 | 0.16 | 0.38 | 0.13 | 0.13 | 0.63 | 2.00 | 0.56 |
| 2762/12 | ST512 | 0.09 | 1.00 | 0.75 | 2.00 | 1.13 | 0.75 | 0.56 | 0.56 | 2.00 | 2.00 |
| 3031/12 | ST512 | 0.16 | 0.25 | 0.25 | 2.00 | 2.00 | 0.38 | 2.00 | 1.00 | 2.00 | 2.00 |
| 3177/12 | ST512 | 0.09 | 0.50 | 0.53 | 0.50 | 2.00 | 1.00 | 0.75 | 2.00 | 2.00 | 1.00 |
| 3325/12 | ST512 | 0.28 | 0.16 | 0.19 | 2.00 | 0.63 | 0.31 | 4.00 | 0.63 | 1.00 | 2.00 |
| 3342/12 | ST512 | 0.09 | 0.63 | 1.00 | 2.00 | 2.00 | 0.63 | 2.00 | 1.00 | 2.00 | 1.00 |
| 3434/12 | ST512 | 0.19 | 0.75 | 0.56 | 1.00 | 3.00 | 0.75 | 2.00 | 2.00 | 2.00 | 2.00 |
| 3515/12 | ST512 | 0.06 | 0.75 | 0.52 | 0.50 | 0.19 | 0.26 | 0.56 | 0.75 | 2.00 | 2.00 |
| 2/12 | ST101 | 0.08 | 2.00 | 0.56 | 2.00 | 2.00 | 0.50 | 2.00 | 2.00 | 2.00 | 2.00 |
| 4306/11 | ST101 | 0.12 | 0.75 | 0.53 | 0.50 | 0.50 | 0.56 | 0.56 | 2.00 | 2.00 | 2.00 |
| 101/11 | ST101 | 0.09 | 2.00 | 0.75 | 2.00 | 2.00 | 2.00 | 2.00 | 2.00 | 2.00 | 2.00 |
| No. (%c) with synergism | 13 (100) | 5 (38.5) | 5 (38.5) | 5 (38.5) | 5 (38.5) | 5 (38.5) | 3 (23.1) | 0 (0) | 0 (0) | 0 (0) | |
a
∑FIC = FIC-A + FIC-B (FIC, fractional inhibitory concentration; FIC-A, MIC of agent A in the presence of agent B divided by MIC of agent A alone; FIC-B, MIC of agent B in the presence of agent A divided by MIC of agent B alone).
b
Shading indicates synergism. CST, colistin; RIF, rifampin; IMI, imipenem; MER, meropenem; GEN, gentamicin; TIG, tigecycline.
c
n = 13 strains tested.