Table 5.
Outcomes of fosfomycin-tigecycline combination using the Checkerboard assay.
| Fosfomycin MIC (mg/L) |
Tigecycline MIC (mg/L) |
|||||||
|---|---|---|---|---|---|---|---|---|
| Isolate | Genotype/MLST | Alone | Combined | Fold Decline |
Alone | Combined | Fold Decline | FICI (x−)/ Interpretation |
| Kp 1 | OXA-232/ ST-231 |
128 | 16 | ≥8 | 2 | ≥32 | - | >4/AN |
| Kp 2 | OXA-232/ ST-231 |
32 | 16 | ≥2 | 4 | ≥32 | - | >4/AN |
| Kp 3 | ST-231 OXA-232 | 64 | 32 | ≥2 | 4 | ≥32 | - | >4/AN |
| Kp 4 | ST-231 NDM-1 | 64 | ≤8 | ≥8 | 4 | 2 | 2 | 0.62/PS |
| Kp 5 | OXA-232/ST-231 | 64 | ≤8 | ≥8 | 4 | 2 | 2 | 0.62/PS |
| Kp 6 | OXA-232/ ST-231 |
64 | 32 | 2 | 4 | ≥32 | - | >4/AN |
| Kp 7 | OXA-232/ST-231 | 64 | ≤8 | ≥8 | 4 | 2 | 2 | 0.62/PS |
| Kp 8 | OXA-232/ST-231 | 64 | ≤8 | ≥8 | 4 | 2 | 2 | 0.62/PS |
| Kp 9 | OXA-232/ST-231 | 64 | ≤8 | ≥8 | 4 | 2 | 2 | 0.62/PS |
| Kp10 | OXA-232/ST-231 | 64 | ≤8 | ≥8 | 2 | 1 | 2 | 0.62/PS |
| Kp 11 | ST-231 NDM-1 | 64 | ≤8 | ≥8 | 4 | 2 | 2 | 0.62/PS |
| Kp 12 | OXA-232/ST-231 | 64 | ≤8 | ≥8 | 4 | 2 | 2 | 0.62/PS |
| Kp 13 | OXA-232/ST-395 | 64 | ≤8 | ≥8 | 2 | 1 | 2 | 0.62/PS |
| Kp 14 | OXA-232/ST-395 | 64 | ≤8 | ≥8 | 2 | 1 | 2 | 0.62/PS |
| Kp 15 | OXA-232/ST-231 | 64 | ≤8 | ≥8 | 2 | 1 | 2 | 0.62/PS |
| Kp 16 | OXA-232+ NDM-5/ST147 | 64 | ≤8 | ≥8 | 4 | 2 | 2 | 0.62/PS |
| Kp 17 | OXA-232/ST-231 | 64 | ≤8 | ≥8 | 2 | 1 | 2 | 0.62/PS |
| Kp 18 | OXA-232/ST-395 | 64 | ≤8 | ≥8 | 2 | 1 | 2 | 0.62/PS |
Abbreviation: FICI = fractional inhibition concentration index, Kp = K. pneumoniae, MIC = minimal inhibition concentration, x− =mean value, PS = partial synergy, AN = antagonism, OXA = Oxacillin carbapenemases, NDM = New Delhi metallo-beta-lactamase.