Table 2.
Fractional inhibitory concentration (FIC) index determined for AgNPs and antibiotics against bacteria and yeasts
| Tested microorganism | FIC index | |||||
|---|---|---|---|---|---|---|
| Ampicilin + AgNPs | Kanamycin + AgNPs | Tetracycline + AgNPs | ||||
| FIC | Conc. of antimicrobial and AgNPs used in determined FIC (µg ml−1) | FIC | Conc. of antimicrobial and AgNPs used in determined FIC (µg ml−1) | FIC | Conc. of antimicrobial and AgNPs used in determined FIC (µg ml−1) | |
|
Escherichia coli
ATCC 8739 |
0.12a | 64 + 4 | 0.12a | 32 + 4 | 0.12 | 4 + 4 |
|
Klebsiella pneumoniae
ATCC 700603 |
0.12a | 64 + 16 | 0.12 | 12 + 16 | 0.12 | 2 + 16 |
| Pseudomonas aeruginosa ATCC 10145 | 2.0 | 768 + 32 | 2.0 | 128 + 32 | 2.0 | 64 + 32 |
|
Staphylococcus aureus
ATCC 6538 |
0.12 | 0.0625 + 16 | 0.12 | 0.5 + 16 | 0.12 | 0.25 + 16 |
|
Bacillus subtilis
PCM 2021 |
0.12 | 0.004 + 4 | 0.12 | 0.125 + 4 | 0.12 | 0.008 + 4 |
| Tested microorganism | FIC index | |||||
|---|---|---|---|---|---|---|
| Amphotericin B + AgNPs | Fluconazole + AgNPs | Ketoconazole + AgNPs | ||||
| FIC | Conc. of antimicrobial and AgNPs used in determined FIC (µg ml−1) | FIC | Conc. of antimicrobial and AgNPs used in determined FIC (µg ml−1) | FIC | Conc. of antimicrobial and AgNPs used in determined FIC (µg ml−1) | |
|
Candida albicans
ATCC 10231 |
0.12 | 0.016 + 2 | 0.12a | 64 + 2 | 0.12a | 64 + 2 |
|
Malassezia furfur
DSM 6170 |
1.0a | 1024 + 32 | 1.0 | 4 + 32 | 0.12a | 64 + 2 |
Reduction of AgNPs concentration after combined use with antibiotics to value ≤ IC50 (about 4 µg ml−1) are highlighted in bold
≤ 0.5 synergism; > 0.5–1.0 non synergistic or additive effect; ≥ 1.0–2.0 indifferent effect (Doern 2014)
aAs the MIC was not determined in the wide concentration range of antibiotic (see Table 1), the highest concentration of antibiotic was used for FIC index determination