Table 2.
Essential oils and volatile compounds modulating the antibiotic activity against Escherichia coli.
| Essential Oil/Volatile Compound | Vegetal Source | Major Constituent | Escherichia coli Strain | Antibiotic | Method | Effect | Ref. |
|---|---|---|---|---|---|---|---|
| Oregano EO | Origani herba (Origanum vulgare Linn., Lamiaceae, Oregano) | Cymenol (58.6%) | ATCC 25922 | Gentamicin | CB (FICI = 0.65) | Ad | [34] |
| Thyme EO | Thymi herba (Thymus maroccanus L., Lamiaceae, Za’ater/Azukeni) | Carvacrol (76.35%) | AG100 | Chloramphenicol | FR (4-fold reduction in MIC) | S | [52] |
| AG102 | FR (32-fold reduction in MIC) | ||||||
| Thymi herba (Thymus broussonetii L., Lamiaceae, Za’atar Essaouiri) | Carvacrol (39.77%) Borneol (12.03%) |
AG100 | FR (4-fold reduction in MIC) | ||||
| AG102 | FR (32-fold reduction in MIC) | ||||||
| Lemon thyme EO | Thymi herba (Thymus pulegioides L., Lamiaceae, Lemon thyme/broad-leaved thyme) | Geraniol (66.59%) | ATCC 25922 | Tetracycline | CB (FICI = 0.43–0.76) | S | [74] |
| CB (FICI = 0.98–1.09) | Ad | ||||||
| Streptomycin | CB (FICI = 1.20–2.80) | A | |||||
| Chloramphenicol | CB (FICI = 0.21–0.87) | S | |||||
| CB (FICI = 0.98–1.09) | Ad | ||||||
| Savory EO | Saturejae herba (Satureja kitaibelii Wierzb. ex Heuff., Lamiaceae, Savory) | Geraniol (50.4%) | ATCC 25922 | Chloramphenicol | CB (FICI = 0.21–0.87) | S | [60] |
| CB (FICI = 0.98–1.09) | Ad | ||||||
| Tetracycline | CB (FICI = 0.32–0.87) | S | |||||
| CB (FICI = 0.98–1.09) | Ad | ||||||
| Sandarac EO | Tetraclinis coni (Tetraclinis articulata (Vahl.) Masters., Cupressaceae, Sandarac) | α-Campholenal (16.34%) Trans-Pinocarveol (15.45%) Verbenone (13.36%) Cis-Verbenol (12.36%) |
ATCC 10536 | Amoxicillin | CB (FICI = 1) | Ad | [75] |
| Rosemary EO | Rosmarini folium (Rosmarinus officinalis L., Lamiaceae, Rosemary) | 1,8-Cineole (30.87%) | Clinical isolate | Amikacin | FR (~250-fold reduction in MIC) | S | [61] |
| Neomycin | FR (~250-fold reduction in MIC) | ||||||
| Gentamicin | FR (~4200-fold reduction in MIC) | ||||||
| Cidreira-do-mato/cidreira-brava EO | Hyptis folium (Hyptis martiusii Benth., Lamiaceae, Cidreira-do-mato/cidreira-brava) | Bicyclogermacrene (10.6%) Trans-Caryophyllene (9.2%) Caryophyllene oxide (7.4%) 1,8-Cineole (7%) |
ATCC 25922 | Amikacin | FR (–) | I | [64] |
| IZGC (+2.4%) | S | ||||||
| Gentamycin | FR (–) | I | |||||
| IZGC (+17.6%) | S | ||||||
| Neomycin | FR (4-fold reduction in MIC) | S | |||||
| Kanamycin | FR (–) | I | |||||
| Tobramycin | IZGC (+76.5%) | S | |||||
| Cidreira-do-mato/cidreira-brava EO | Hyptis folium (Hyptis martiusii Benth., Lamiaceae, Cidreira-do-mato/cidreira-brava) | Bicyclogermacrene (10.6%) Trans-Caryophyllene (9.2%) Caryophyllene oxide (7.4%) 1,8-Cineole (7%) |
Clinical isolate | Amikacin | FR (–) | I | [64] |
| IZGC (+82.4%) | S | ||||||
| Gentamycin | FR (–) | I | |||||
| IZGC (+40.0%) | S | ||||||
| Neomycin | FR (–) | I | |||||
| Kanamycin | FR (–) | I | |||||
| Tobramycin | IZGC (+80.0%) | S | |||||
| Thyme EO | Thymi herba (Thymus riatarum Humbert and Maire., Lamiaceae, Moroccan thyme) | Borneol (41.67%) | AG100 | Chloramphenicol | FR (4-fold reduction in MIC) | S | [58] |
| AG100A | FR (2-fold reduction in MIC) | ||||||
| Thyme EO | Thymi herba (Thymus saturejoides Coss., Lamiaceae, Azoukni) | Carvacrol (25.3%) Borneol (19.7%) |
ATCC 25922 | Cefixime | CB (FICI = 1.25) | I | [76] |
| Carvacrol (26.5%) Borneol (20.1%) | |||||||
| Carvacrol (45.3%) Borneol (7.5%) | |||||||
| Rosewood EO | Anibae lignum (Aniba rosaeodora Ducke, Lauraceae, Rosewood) | Linalool (60.1%) | ATCC 25922 | Gentamicin | CB (FICI = 0.35) | S | [34] |
| Geranium EO | Pelargonii herba (Pelargonium graveolens L’Hér., Geraniaceae, Geranium) | Citronellol (47.3%) | ATCC 25922 | Gentamicin | CB (FICI = 0.30) | S | [34] |
| Tea tree EO | Melaleucae folium (Melaleuca alternifolia (Maiden. and Beach.) Cheel., Myrtaceae, Tea tree) | Terpinen-4-ol (30.3%) | ATCC 25922 | Gentamicin | CB (FICI = 0.49) | S | |
| Citronellol | - | Clinical isolate | Penicillin | CB (FICI = 1.03) | I | [65] | |
| Geraniol | - | Clinical isolate | Penicillin | CB (FICI = 1.5) | I | [60] | |
| ATCC 25922 | Chloramphenicol | CB (FICI = 0.32–0.87) | S | ||||
| CB (FICI = 0.98–1.09) | Ad | ||||||
| Tetracycline | CB (FICI = 0.32–0.87) | S | |||||
| CB (FICI = 0.98–1.28) | Ad | ||||||
| Menthol | - | Clinical isolate | Penicillin | CB (FICI = 1.5) | I | [65] | |
| Myrcene | - | Clinical isolate | Penicillin | CB (FICI = 10) | A | ||
| Thymol | - | Clinical isolate | Penicillin | CB (FICI = 0.15) | S | [65] | |
| N00 666 | Ampicillin | CB (FICI = 0.12) | S | [66] | |||
| Penicillin | CB (FICI = 0.20) | ||||||
| Tetracycline | CB (FICI = 0.15) | ||||||
| Erythromycin | CB (FICI = 0.25) | ||||||
| Bacitracin | CB (FICI = 0.56) | I | |||||
| Novobiocin | CB (FICI = 0.37) | S | |||||
| Eugenol | - | Clinical isolate | Penicillin | CB (FICI = 0.16) | S | [65] | |
| N00 666 | Ampicillin | CB (FICI > 0.5) | I | [66] | |||
| Penicillin | |||||||
| Tetracycline | CB (FICI = 0.16) | S | |||||
| Erythromycin | CB (FICI = 1.1) | I | |||||
| Bacitracin | CB (FICI = 0.5) | S | |||||
| Novobiocin | CB (FICI = 1.1) | I | |||||
| Carvacrol | - | Clinical isolate | Penicillin | CB (FICI = 2) | I | [65] | |
| N00 666 | Ampicillin | CB (FICI = 0.25) | S | [66] | |||
| Penicillin | CB (FICI = 0.37) | ||||||
| Tetracycline | CB (FICI = 0.15) | ||||||
| Erythromycin | CB (FICI = 1.0) | I | |||||
| Bacitracin | CB (FICI = 0.25) | S | |||||
| Novobiocin | CB (FICI = 0.63) | I | |||||
| Cinnamaldehyde | - | N00 666 | Ampicillin | CB (FICI = 0.37) | S | [66] | |
| Penicillin | CB (FICI = 0.24) | ||||||
| Tetracycline | CB (FICI = 0.37) | ||||||
| Erythromycin | CB (FICI = 0.24) | ||||||
| Bacitracin | CB (FICI = 0.63) | I | |||||
| Novobiocin | CB (FICI = 0.24) | S | |||||
| Allyl isothiocyanate | - | N00 666 | Ampicillin | CB (FICI = 0.63) | I | ||
| Penicillin | CB (FICI = 1.0) | ||||||
| Tetracycline | CB (FICI = 0.75) | ||||||
| Erythromycin | CB (FICI = 0.73) | ||||||
| Bacitracin | CB (FICI = 0.5) | S | |||||
| Novobiocin | CB (FICI = 1.0) | I | |||||
A: antagonism; Ad: addition; I: indifference; S: synergy; CB: checkerboard assay; FICI: fractional inhibitory concentration index; FR: fold reduction in MIC; MIC: minimum inhibitory concentration; IZGC (%): percentage change in inhibition zone diameter due to gaseous contact with essential oil/volatile component.