Table 4.
MIC of antibiotics after the association of resveratrol (4) at MIC/2 and MIC/4 against selected MDR bacteria
| Antibioticsa | Concentration of 4 | Bacteria strainsb, MIC of antibiotics alone and in presence of 4 (Resveratrol), FIC (in bracket ) | PBSS (%)c | |||||
|---|---|---|---|---|---|---|---|---|
| PA124 | CM64 | KP55 | AG102 | AG100Atet | PS2636 | |||
| CHL | 0 | 256 | 128 | 32 | 64 | 64 | 256 | |
| MIC/2 | 32 (0.25)S | 2(0.02)S | 16(0.5)S | 64(1)I | <2(<0.03)S | 64(0.25)S | 5/6 (83.3 %) | |
| MIC/4 | 32(0.25)S | 4(0.03)S | 16(0.5)S | 64(1)I | <2 (<0.03)S | 64(0.25)S | 5/6(83.3 %) | |
| KAN | 0 | 128 | 64 | 64 | 4 | 32 | 4 | |
| MIC/2 | 64(0.5)S | <2 (<0.03)S | 32(0.5)S | <2 (<0.5)S | <2(0.06)S | 4(1)I | 5/6(83.3 %) | |
| MIC/4 | 64(0.5)S | <2 (<0.03)S | 32(0.5)S | <2 (<0.5)S | <2(0.06)S | 4(1)I | 5/6(83.3 %) | |
| STR | 0 | 64 | 128 | 64 | ≤2 | − | ≤2 | |
| MIC/2 | 32(0.5)S | 64(0.5)S | 16(0.25)S | <2 na | 64(≤0.5)S | <2 na | 4/4 (100 %) | |
| MIC/4 | 32(0.5)S | 64(0.5)S | 32(0.5)S | 4(>2) na | 128(≤0.5)S | <2 na | 4/4 (100 %) | |
| CIP | 0 | 64 | 8 | 4 | 1 | 64 | 4 | |
| MIC/2 | 4(0.06)S | <2(0.25)S | <2(<0.5)S | <0.5(<0.5)S | <2(<0.03)S | 8(2)I | 5/6(83.3 %) | |
| MIC/4 | 16(0.25)S | <2(0.25)S | <2(<0.5)S | <0.5(<0.5)S | <2(<0.03)S | <0.5(<0.13)S | 6/6 (100 %) | |
| TET | 0 | 64 | 64 | 32 | 4 | 256 | 64 | |
| MIC/2 | 4(0.06)S | 64(1)I | 32(1)I | <2(<0.5)S | 256(1)I | 32(0.5)S | 3/6 (50 %) | |
| MIC/4 | 4(0.06)S | 128(2)I | 16(0.5)S | <2(<0.5)S | 256(1)I | 16(0.25)S | 4/6 (66.7 %) | |
(−): >256 μg/mL; 0: without compound 4 (only antibiotic tested). CIP have been tested at 64 μg/ml on AG102 and PS2636; na: non-applicable; Values in bold: MIC of antibiotic alone or significant synergistic effects
S Synergy, I Indifference, A Antagonism, P product, FIC fractional inhibitory concentration
aAntibiotics [CHL: chloramphenicol, KAN : kanamycin, STR: streptomycin, CIP : ciprofloxacin, TET : tetracycline]
bBacterial strains: Escherichia coli [ AG102, AG100Atet], Pseudomonas aeruginosa [PA124], Enterobacter aerogenes [CM64], Klebsiella pneumoniae [KP55], Providencia stuartii [PS2636]
cPBSS: percentage of bacteria strain on which synergism has been observed