Table 6.
Resistance modulating effects of the bark methanol extract from Syzygium jambos at its subinhibitory concentrations on selected S. aureus strains.
| Antibiotics | Bacterial strains, MIC (μg/mL) of antibiotics in the absence and presence of the extract | ||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|
| Extract concentration | ATCC 25923 | MRSA3 | MRSA4 | MRSA9 | MRSA11 | MRSA12 | SA18 | SA36 | SA64 | Antibiotic modulating effect (%) | |
| CIP | 0 | 8 | ≤0.5 | 8 | ≤0.5 | 1 | 2 | 2 | 4 | 8 | |
| MIC/2 | 8 (1) | ≤0.5 (na) | 8 (1) | ≤0.5 (na) | 1 (1) | 2 (1) | 2 (1) | 2 (2) | ≤0.5 (≥16) | 22.22 | |
| MIC/4 | 8 (1) | ≤0.5 (na) | 16 (0.5) | ≤0.5 (na) | 1 (1) | 2 (1) | 2 (1) | 2 (2) | ≤0.5 (≥16) | 22.22 | |
| CHL | 0 | 64 | 64 | 4 | 128 | 128 | 128 | 8 | 128 | 32 | |
| MIC/2 | ≤2 (≥32) | 32 (2) | ≤2 (≥2) | 64 (2) | 128 (1) | 64 (2) | ≤2 (≥4) | 64 (2) | ≤2 (≥16) | 88.89 | |
| MIC/4 | 64 (1) | 32 (2) | 4 (1) | 64 (2) | 128 (1) | 64 (2) | ≤2 (≥4) | 128 (1) | ≤2 (≥16) | 55.56 | |
| TET | 0 | ≤0.5 | 32 | 2 | 32 | 64 | 64 | 2 | 1 | 1 | |
| MIC/2 | ≤0.5 (na) | 32 (1) | ≤0.5 (≥4) | 32 (1) | 32 (2) | 64 (1) | 1 (2) | 1 (1) | ≤0.5 (≥2) | 44.44 | |
| MIC/4 | ≤0.5 (na) | 32 (1) | ≤0.5 (≥4) | 32 (1) | 32 (2) | 64 (1) | 1 (2) | 1 (1) | ≤0.5 (≥2) | 44.44 | |
| ERY | 0 | 16 | 32 | 16 | 8 | 16 | 16 | 32 | ≤2 | 8 | |
| MIC/2 | ≤2 (≥8) | 16 (2) | ≤2 (≥8) | 8 (1) | 16 (1) | 16 (1) | 32 (1) | ≤2 (na) | ≤2 (≥4) | 44.44 | |
| MIC/4 | ≤2 (≥8) | 16 (2) | 4 (4) | 8 (1) | 16 (1) | 16 (1) | 32 (1) | ≤2 (na) | ≤2 (≥4) | 44.44 | |
| KAN | 0 | ≤2 | 8 | 256 | 16 | 16 | 64 | 8 | ≤2 | 32 | |
| MIC/2 | ≤2 (na) | 4 (2) | 256 (1) | 16 (1) | 16 (1) | 16 (4) | ≤2 (≥4) | ≤2 (na) | ≤2 (≥16) | 44.44 | |
| MIC/4 | ≤2 (na) | 8 (1) | 256 (1) | 16 (1) | 16 (1) | 32 (2) | ≤2 (≥4) | ≤2 (na) | ≤2 (≥16) | 33.33 | |
| CEF | 0 | - | - | - | - | - | - | - | 32 | 128 | |
| MIC/2 | - | - | - | - | - | - | - | 4 (8) | 8 (16) | 22.22 | |
| MIC/4 | - | - | - | - | - | - | - | 16 (2) | 64 (2) | 22.22 | |
| STR | 0 | 256 | 128 | 64 | 128 | 64 | 64 | 128 | 128 | 16 | |
| MIC/2 | 64 (4) | 64 (2) | ≤2 (≥32) | 64 (2) | 64 (1) | 64 (1) | 64 (2) | 128 (1) | 4 (4) | 66.67 | |
| MIC/4 | 256 (1) | 64 (2) | 64 (1) | 64 (2) | 64 (1) | 64 (1) | 64 (2) | 128 (1) | 4 (4) | 44.44 | |
| AMP | 0 | - | - | 256 | - | - | - | 128 | 256 | - | |
| MIC/2 | - | - | 256 (1) | - | - | - | 128 (1) | ≤2 (≥128) | - | 11.11 | |
| MIC/4 | - | - | 256 (1) | - | - | - | 128 (1) | 256 (1) | - | 0 | |
TET: tetracycline, KAN: kanamycin, ERY: erythromycin, CHL: chloramphenicol, CIP: ciprofloxacin, AMP: ampicillin, STR: streptomycin, CEF: cefepime; (-): MIC not detected at up to 256 μg/mL; (): modulating factor; na: not applicable; MIC: minimum inhibitory concentration; percentage of antibiotic's modulating effect by the plant extracts; values in bold represent modulating factor ≥ 2 and modulating effect observed on more than 70% of the tested MDR bacteria.