Table 4.
Antimicrobial activity of combinations of AMPs with antibiotics against drug-resistant clinical isolates.
| Minimal FICIsa of antibiotic(AB)\AMP combinations against drug-resistant clinical isolates | ||||||||||
|---|---|---|---|---|---|---|---|---|---|---|
| Gram-negative | Gram-positive | |||||||||
| E. coli ESBL 521/17 | A. baumannii 7226/16 | P. aeruginosa MDR 522/17 | K. pneumoniae ESBL 344/17 | S. aureus 1399/17 | ||||||
| AB\AMP | PG-1 | ChBac3.4 | PG-1 | ChBac3.4 | PG-1 | ChBac3.4 | PG-1 | ChBac3.4 | PG-1 | ChBac3.4 |
| OX | 1.12 | 1.12 | 0.75 | 1.12 | 1.12 | 1.12 | 1.12 | 1.12 | 1.12 | 0.25* |
| MEM | 1.0 | 1.0 | 0.38* | 0.5* | 1.0 | 0.62 | 1.0 | 1.0 | 0.25* | 0.31* |
| ERY | 0.62 | 0.38* | 1.12 | 0.75 | 0.5* | 0.38* | 0.25* | 0.25* | 0.75 | 0.5* |
| AMK | 0.38 | 0.62 | 0.38* | 0.5* | 0.5 | 0.5 | 0.31 | 0.38 | 1.0 | 0.125* |
| OFL | 0.75 | 0.75 | 0.62 | 0.5* | 1.12 | 0.75 | 0.5 | 0.75 | 0.56 | 0.125* |
AMP, antimicrobial peptide; OX, oxacillin; MEM, meropenem; ERY, erythromycin; AMK, amikacin; OFL, ofloxacin.
a
Fractional Inhibitory Concentration Indices (FICI) values are medians of 3–6 independent experiments; FICI > 2 indicates antagonism, 1 < FICI ≤ 2 shows independent action, 0.5 < FICI ≤ 1 corresponds to additivity, FICI ≤ 0.5 denotes synergy; synergy cases are set off in bold type.
*
Bacterium has moderate or high resistance to the antibiotic being part of the synergistic combination.