Table 2.
Checkerboard analysis of combined effects of honey and antibiotics on S. aureus growth and biofilm formation.
| Antibacterial agent |
Planktonic growth inhibition |
Biofilm prevention |
||||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Antibiotic MIC (μg/mL) |
Honey MIC (μg/mL) |
FICI | Synergy (<0.5) | Antibiotic MBIC (μg/mL) |
Honeys MBIC (μg/mL) |
FICI | Synergy (<0.5) | |||||||
| Antibiotic1 | Honey | Alone | Combined with honey | Alone | Combined with antibiotic | Alone | Combined with honey | Alone | Combined with antibiotic | |||||
| NCTC8325 | Rifampicin | Medihoney | 0.039 | 0.0024 | 8 | 3 | 0.445 | ✓ | 0.039 | 0.0024 | 8 | 3 | 0.445 | ✓ |
| Rifampicin | Manuka | 0.039 | 0.0024 | 8 | 3 | 0.445 | ✓ | 0.039 | 0.0024 | 8 | 3 | 0.445 | ✓ | |
| Clindamycin | Medihoney | 0.3 | 0.01 | 8 | 3 | 0.405 | ✓ | 0.3 | 0.01 | 8 | 3 | 0.405 | ✓ | |
| Clindamycin | Manuka | 0.3 | 0.01 | 8 | 3 | 0.405 | ✓ | 0.3 | 0.01 | 8 | 3 | 0.405 | ✓ | |
| Gentamicin | Medihoney | 0.6 | 0.2 | 8 | 7 | 1.195 | 0.6 | 0.2 | 8 | 7 | 1.195 | |||
| Gentamicin | Manuka | 0.6 | 0.002 | 8 | 7 | 0.8782 | 0.6 | 0.0024 | 8 | 7 | 0.8782 | |||
| Oxacillin | Medihoney | 0.25 | 0.008 | 8 | 3 | 0.405 | ✓ | 0.25 | 0.008 | 8 | 3 | 0.405 | ✓ | |
| Oxacillin | Manuka | 0.25 | 0.008 | 8 | 3 | 0.405 | ✓ | 0.25 | 0.008 | 8 | 3 | 0.405 | ✓ | |
| MW2 | Rifampicin | Medihoney | 0.039 | 0.0024 | 8 | 3 | 0.435 | ✓ | 0.039 | 0.0024 | 8 | 3 | 0.435 | ✓ |
| Rifampicin | Manuka | 0.039 | 0.0024 | 8 | 3 | 0.435 | ✓ | 0.039 | 0.0024 | 8 | 3 | 0.435 | ✓ | |
| Clindamycin | Medihoney | 0.3 | 0.01 | 8 | 3 | 0.405 | ✓ | 0.3 | 0.01 | 8 | 3 | 0.405 | ✓ | |
| Clindamycin | Manuka | 0.3 | 0.03 | 8 | 3 | 0.475 | ✓ | 0.3 | 0.01 | 8 | 3 | 0.475 | ✓ | |
| Gentamicin | Medihoney | 0.625 | 0.2 | 8 | 5 | 0.945 | 0.625 | 0.2 | 8 | 5 | 0.945 | |||
| Gentamicin | Manuka | 0.625 | 0.2 | 8 | 6 | 1.07 | 0.625 | 0.2 | 8 | 6 | 1.07 | |||
| Oxacillin | Medihoney | >20 | 0.06(S)2 | 8 | 6 | 0.753 | >20 | 0.06 | 8 | 6 | 0.753 | |||
| Oxacillin | Manuka | >20 | 0.06(S) | 8 | 6 | 0.753 | >20 | 0.06 | 8 | 6 | 0.753 | |||
| 04-227-3567 | Rifampicin | Medihoney | 0.039 | 0.0024 | 8 | 3 | 0.445 | ✓ | 0.039 | 0.0024 | 8 | 2 | 0.32 | ✓ |
| Rifampicin | Manuka | 0.039 | 0.0024 | 8 | 3 | 0.445 | ✓ | 0.039 | 0.0024 | 8 | 2 | 0.32 | ✓ | |
| Clindamycin | Medihoney | 0.3 | 0.01 | 8 | 3 | 0.405 | ✓ | 0.3 | 0.01 | 8 | 3 | 0.405 | ✓ | |
| Clindamycin | Manuka | 0.3 | 0.01 | 8 | 3 | 0.405 | ✓ | 0.3 | 0.01 | 8 | 3 | 0.405 | ✓ | |
| Gentamicin | Medihoney | 0.5 | 0.16 | 8 | 5 | 0.955 | 0.5 | 0.16 | 8 | 5 | 0.945 | |||
| Gentamicin | Manuka | 0.5 | 0.16 | 8 | 5 | 0.955 | 0.5 | 0.16 | 8 | 5 | 0.945 | |||
| Oxacillin | Medihoney | 0.25 | 0.008 | 8 | 3 | 0.407 | ✓ | 0.25 | 0.008 | 8 | 3 | 0.407 | ✓ | |
| Oxacillin | Manuka | 0.25 | 0.008 | 8 | 3 | 0.407 | ✓ | 0.25 | 0.008 | 8 | 3 | 0.407 | ✓ | |
| RPAH18 | Rifampicin | Medihoney | 0.078 | 0.0024 | 8 | 3 | 0.405 | ✓ | 0.078 | 0.0024 | 8 | 3 | 0.36 | ✓ |
| Rifampicin | Manuka | 0.078 | 0.0024 | 8 | 3 | 0.405 | ✓ | 0.078 | 0.0024 | 8 | 3 | 0.36 | ✓ | |
| Clindamycin | Medihoney | >20 | >20 | 8 | 8 | 2 | >20 | >20 | 8 | 8 | 2 | |||
| Clindamycin | Manuka | >20 | >20 | 8 | 8 | 2 | >20 | >20 | 8 | 8 | 2 | |||
| Gentamicin | Medihoney | >20 | >20 | 8 | 8 | 2 | >20 | >20 | 8 | 8 | 2 | |||
| Gentamicin | Manuka | >20 | >20 | 8 | 8 | 2 | >20 | >20 | 8 | 8 | 2 | |||
| Oxacillin | Medihoney | >20 | 0.06(S) | 8 | 7 | 0.8782 | >20 | >20 | 8 | 7 | 0.7832 | |||
| Oxacillin | Manuka | >20 | 0.06(S) | 8 | 6 | 0.8782 | >20 | 0.06 | 8 | 6 | 0.6732 | |||
1Data for rifampicin is copied with permission from Müller et al. (2013).
2S = clinically susceptible to oxacillin based on EUCAST breakpoints (EUCAST, 2014) for S. aureus (S < 2 μg/mL).