Table 1.
Minimum inhibitory concentration (MIC), minimum bactericidal concentration (MBC), MBC/MIC ratio and effectiveness of the investigated substances against Klebsiella pneumoniae strains.
| Bacteria | Chemicals | MIC (mg/mL) |
MBC (mg/mL) |
MBC/MIC | Effectiveness |
|---|---|---|---|---|---|
| Reference strain (K. pneumoniae ATCC BAA-2473) |
Linalool | 6.48 ± 0.00 | 51.88 ± 0.00 | 8 | bacteriostatic |
| β-Citronellol | 6.70 ± 0.00 | 107.13 ± 0.00 | 16 | bacteriostatic | |
| Menthone | 224.00 ± 0.00 | >448 | ND | ND | |
| Geraniol | 1.74 ± 0.00 | 6.95 ± 0.00 | 4 | bactericidal | |
| Eugenol | 4.14 ± 0.00 | >530 | ND | ND | |
| Thymol | 0.78 ± 0.00 | 1.56 ± 0.00 | 2 | bactericidal | |
| 1,8-Cineole | 57.63 ± 0.00 | 461.00 ± 0.00 | 8 | bacteriostatic | |
| Carvacrol | 1.91 ± 0.00 | 1.91 ± 0.00 | 1 | bactericidal | |
| Gentamicin | 1.25 ± 0.00 | >40 | ND | ND | |
| Isolate no. 1 | Linalool | 3.24 ± 0.00 | 25.94 ± 0.00 | 8 | bacteriostatic |
| β-Citronellol | 26.78 ± 0.00 | 107.13 ± 0.00 | 4 | bactericidal | |
| Menthone | 448.00 ± 0.00 | >448 | ND | ND | |
| Geraniol | 3.47 ± 0.00 | 6.95 ± 0.00 | 2 | bactericidal | |
| Eugenol | 4.14 ± 0.00 | >530 | ND | ND | |
| Thymol | 0.78 ± 0.00 | 1.56 ± 0.00 | 2 | bactericidal | |
| 1,8-Cineole | 14.41 ± 0.00 | 461.00 ± 0.00 | 32 | bacteriostatic | |
| Carvacrol | 1.91 ± 0.00 | 1.91 ± 0.00 | 1 | bactericidal | |
| Gentamicin | 20.00 ± 0.00 | 40.00 ± 0.00 | 2 | bactericidal | |
| Isolate no. 2 | Linalool | 1.62 ± 0.00 | 25.94 ± 0.00 | 16 | bacteriostatic |
| β-Citronellol | 3.35 ± 0.00 | 107.13 ± 0.00 | 32 | bacteriostatic | |
| Menthone | 224.00 ± 0.00 | >448 | ND | ND | |
| Geraniol | 1.74 ± 0.00 | 6.95 ± 0.00 | 4 | bactericidal | |
| Eugenol | 4.14 ± 0.00 | >530 | ND | ND | |
| Thymol | 0.78 ± 0.00 | 1.56 ± 0.00 | 2 | bactericidal | |
| 1,8-Cineole | 14.41 ± 0.00 | >461 | ND | ND | |
| Carvacrol | 1.91 ± 0.00 | 1.91 ± 0.00 | 1 | bactericidal | |
| Gentamicin | 20.00 ± 0.00 | 40.00 ± 0.00 | 2 | bactericidal | |
| Isolate no. 3 | Linalool | 3.24 ± 0.00 | 103.75 ± 0.00 | 32 | bacteriostatic |
| β-Citronellol | 1.67 ± 0.00 | 107.13 ± 0.00 | 64 | bacteriostatic | |
| Menthone | 224.00 ± 0.00 | >448 | ND | ND | |
| Geraniol | 0.87 ± 0.00 | 6.95 ± 0.00 | 8 | bacteriostatic | |
| Eugenol | 4.14 ± 0.00 | >530 | ND | ND | |
| Thymol | 0.78 ± 0.00 | 1.56 ± 0.00 | 2 | bactericidal | |
| 1,8-Cineole | 461.00 ± 0.00 | >461 | ND | ND | |
| Carvacrol | 1.91 ± 0.00 | 1.91 ± 0.00 | 1 | bactericidal | |
| Gentamicin | 1.25 ± 0.00 | >40 | ND | ND |
Legend: ND—not determined. Gentamicin was used as positive control.