Table 8. Chequerboard results of colistin in combination with fosfomycin, tetracyclines (minocycline, and tigecycline) and penicillin (piperacillin) against colistin resistant K. pneumoniae isolates.
| Isolates | Antibiotics | Combined MIC (μg/mL) | FICI | Fold reduction | Outcome |
|---|---|---|---|---|---|
| 1NT4Ng/1 | COL | 64 | 0.500 | 4 | Synergy |
| FOS | 256 | 4 | |||
| COL | 16 | 0.093 | 16 | Synergy | |
| MIN | 4 | 32 | |||
| COL | ND | ND | ND | ND | |
| TIG | ND | ||||
| COL | 32 | 0.128 | 8 | Synergy | |
| PIP | 4 | 256 | |||
| 1NT6Ng/1 | COL | 64 | 0.375 | 4 | Synergy |
| FOS | 128 | 8 | |||
| COL | 16 | 0.093 | 16 | Synergy | |
| MIN | 4 | 32 | |||
| COL | ND | ND | ND | ND | |
| TIG | ND | ||||
| COL | 32 | 0.187 | 8 | Synergy | |
| PIP | 64 | 16 | |||
| 1NT6Tu/1 | COL | ND | ND | ND | ND |
| FOS | ND | ||||
| COL | 16 | 0.093 | 16 | Synergy | |
| MIN | 4 | 32 | |||
| COL | ND | ND | ND | ND | |
| TIG | ND | ||||
| COL | 32 | 0.126 | 8 | Synergy | |
| PIP | 2 | 512 | |||
| 1NT6R | COL | ND | ND | ND | ND |
| FOS | ND | ||||
| COL | 16 | 0.093 | 16 | Synergy | |
| MIN | 4 | 32 | |||
| COL | ND | ND | ND | ND | |
| TIG | ND | ||||
| COL | 64 | 0.251 | 4 | Synergy | |
| PIP | 2 | 512 | |||
| 1NT7R | COL | 64 | 0.500 | 4 | Synergy |
| FOS | 256 | 4 | |||
| COL | 16 | 0.093 | 16 | Synergy | |
| MIN | 4 | 32 | |||
| COL | ND | ND | ND | ND | |
| TIG | ND | ||||
| COL | ND | ND | ND | ND | |
| PIP | ND | ||||
| 1NT8Th | COL | 64 | 0.500 | 4 | Synergy |
| FOS | 256 | 4 | |||
| COL | 16 | 0.093 | 16 | Synergy | |
| MIN | 4 | 32 | |||
| COL | ND | ND | ND | ND | |
| TIG | ND | ND | |||
| COL | 64 | 0.251 | 4 | Synergy | |
| PIP | 2 | 512 | |||
| 1NT6Ng(CCU)/1 | COL | 32 | 0.078 | 16 | Synergy |
| FOS | 2 | 64 | |||
| COL | 16 | 0.093 | 32 | Synergy | |
| MIN | 2 | 16 | |||
| COL | ND | ND | ND | ND | |
| TIG | ND | ||||
| COL | 16 | 0.046 | 32 | Synergy | |
| PIP | 16 | 64 | |||
| 1NT6Th(CCU)/1 | COL | 8 | 0.062 | 32 | Synergy |
| FOS | 4 | 32 | |||
| COL | 8 | 0.093 | 32 | Synergy | |
| MIN | 2 | 16 | |||
| COL | ND | ND | ND | ND | |
| TIG | ND | ||||
| COL | 16 | 0.066 | 16 | Synergy | |
| PIP | 4 | 256 | |||
| 1NT6R(CCU) | COL | 32 | 0.375 | 8 | Synergy |
| FOS | 256 | 4 | |||
| COL | 8 | 0.062 | 32 | Synergy | |
| MIN | 4 | 32 | |||
| COL | ND | ND | ND | ND | |
| TIG | ND | ||||
| COL | 64 | 0.251 | 4 | Synergy | |
| PIP | 2 | 512 | |||
| 1TR5R | COL | 256 | 0.500 | 4 | Synergy |
| FOS | 0.125 | 4 | |||
| COL | ND | ND | ND | ND | |
| MIN | ND | ||||
| COL | ND | ND | ND | ND | |
| TIG | ND | ||||
| COL | 128 | 0.375 | 8 | Synergy | |
| PIP | 0.125 | 4 |
CCU, Cardiac Care Unit; MIC, Minimum inhibitory concentrations; COL, Colistin; FICI, Fractional inhibitory concentration index; FOS, Fosfomycin; MIN, Minocycline; PIP, Piperacillin; TIG, Tigecycline; ND, not determined.