Table 4.
Extent of bacterial killing exerted by antibiotics alone and in combination (time-kill curve) over time against CRAB clinical strains
| Antibiotics and concentrations (mg/L) | No. of isolates showing the following log10 cfu/ml decrease at the designated incubation time | ||||||||||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| 1.h | 2.h | 4. h | 6.h | 24.h | |||||||||||||||
| − 1 | − 2 | − 3 | − 1 | − 2 | − 3 | − 1 | − 2 | − 3 | − 1 | − 2 | − 3 | − 1 | − 2 | − 3 | |||||
| CSA-13a | |||||||||||||||||||
| 0.5×MIC | 2 | 0 | 0 | 3 | 1 | 0 | 0 | 3 | 1 | 1 | 0 | 0 | 0 | 0 | 0 | ||||
| 1×MIC | 4 | 0 | 0 | 1 | 2 | 1 | 0 | 1 | 3 | 0 | 3 | 1 | 0 | 0 | 0 | ||||
| 2×MIC | 3 | 1 | 0 | 0 | 2 | 2 | 0 | 0 | 4 | 0 | 3 | 1 | 0 | 0 | 0 | ||||
| CSA-131a | |||||||||||||||||||
| 0.5×MIC | 3 | 0 | 0 | 1 | 3 | 0 | 0 | 4 | 0 | 4 | 0 | 0 | 0 | 0 | 0 | ||||
| 1×MIC | 4 | 0 | 0 | 0 | 4 | 0 | 0 | 4 | 0 | 3 | 1 | 0 | 0 | 0 | 0 | ||||
| 2×MIC | 3 | 1 | 0 | 0 | 0 | 4 | 0 | 0 | 3 | 0 | 4 | 0 | 0 | 0 | 0 | ||||
| Colistina | |||||||||||||||||||
| 0.5×MIC | 1 | 0 | 0 | 3 | 1 | 0 | 0 | 4 | 0 | 3 | 1 | 0 | 0 | 0 | 0 | ||||
| 1×MIC | 4 | 0 | 0 | 0 | 3 | 1 | 0 | 1 | 2 | 0 | 4 | 0 | 0 | 0 | 0 | ||||
| 2×MIC | 3 | 0 | 0 | 0 | 3 | 1 | 0 | 1 | 1 | 0 | 4 | 0 | 0 | 0 | 0 | ||||
| CSA-13 + Colistinb | |||||||||||||||||||
| 0.5××MIC | 1 | 0 | 0 | 2 | 0 | 0 | 1 | 1 | 0 | 3 | 0 | 0 | 2 | 1 | 1 | ||||
| 1×MIC | 1 | 2 | 0 | 4 | 0 | 0 | 3 | 1 | 0 | 3 | 1 | 0 | 2 | 2 | 0 | ||||
| 2×MIC | 3 | 1 | 0 | 2 | 2 | 0 | 4 | 0 | 0 | 4 | 0 | 0 | 3 | 1 | 0 | ||||
| CSA-131 + Colistinb | |||||||||||||||||||
| 0.5×MIC | 0 | 0 | 0 | 2 | 1 | 0 | 3 | 1 | 0 | 4 | 0 | 0 | 4 | 0 | 0 | ||||
| 1×MIC | 1 | 0 | 0 | 1 | 0 | 0 | 3 | 0 | 0 | 4 | 0 | 0 | 2 | 2 | 0 | ||||
| 2×MIC | 1 | 0 | 0 | 1 | 0 | 0 | 4 | 0 | 0 | 3 | 1 | 0 | 3 | 1 | 0 | ||||
| CSA-13 + CSA 131b | |||||||||||||||||||
| 0.5×MIC | 0 | 0 | 0 | 2 | 0 | 0 | 3 | 1 | 0 | 4 | 0 | 0 | 3 | 1 | 0 | ||||
| 1×MIC | 1 | 0 | 0 | 1 | 0 | 0 | 1 | 1 | 1 | 4 | 0 | 0 | 4 | 0 | 0 | ||||
| 2×MIC | 1 | 0 | 0 | 3 | 0 | 0 | 3 | 0 | 0 | 4 | 0 | 0 | 2 | 2 | 0 | ||||
aBactericidal activity was defined as a ≥ 3-log10 cfu/ml decrease from the initial inoculum
bSynergy was defined as a 100-fold increase in colony count at 24 h by the combination compared with the most active agent alone