Table 3.
Essential oils and volatile compounds modulating the antibiotic activity against Klebsiella pneumoniae.
| Essential Oil/Volatile Compound | Vegetal Source | Major Constituent | Klebsiella pneumoniae Strain | Antibiotic | Method | Effect | Ref. |
|---|---|---|---|---|---|---|---|
| Peppermint EO | Menthae folium (Mentha piperita L., Lamiaceae, Peppermint) | - | NCTC 9633 | Ciprofloxacin | CB (FICI = 0.68–0.90) | S | [2] |
| CB (FICI = 1.40–2.24) | A | ||||||
| Rosemary EO | Rosmarini folium (Rosmarinus officinalis L., Lamiaceae, Rosemary) | - | NCTC 9633 | Ciprofloxacin | CB (FICI = 0.28–0.97) | S | |
| CB (FICI = 1.03–1.07) | A | ||||||
| Thyme EO | Thymi herba (Thymus vulgaris L., Lamiaceae, Thyme) | - | NCTC 9633 | Ciprofloxacin | CB (FICI = 0.71–0.90) | S | |
| CB (FICI = 1.10–1.40) | A | ||||||
| Thyme EO | Thymi herba (Thymus maroccanus L., Lamiaceae, Za’ater/Azukeni) | Carvacrol (76.35%) | Clinical isolate | Ciprofloxacin | CB (FICI = 0.37) | S | [57] |
| Gentamicin | CB (FICI = 0.50) | S | |||||
| Pristinamycin | CB (FICI = 0.50) | S | |||||
| Cefixime | CB (FICI = 1) | I | |||||
| Thyme EO | Thymi herba (Thymus broussonetii L., Lamiaceae, Za’atar Essaouiri) | Carvacrol (39.77%) Borneol (12.03%) |
Ciprofloxacin | CB (FICI = 0.62) | PS | ||
| Gentamicin | CB (FICI = 0.62) | PS | |||||
| Pristinamycin | CB (FICI = 0.50) | S | |||||
| Cefixime | CB (FICI = 1) | I | |||||
| Lemon thyme EO | Thymi herba (Thymus pulegioides L., Lamiaceae, Lemon thyme/broad-leaved thyme) | Geraniol (66.59%) | ATCC 700603 | Tetracycline | CB (FICI = 0.76–0.82) | S | [74] |
| CB (FICI = 0.92–1.10) | Ad | ||||||
| CB (FICI = 1.16–1.28) | A | ||||||
| Streptomycin | CB (FICI = 0.32–0.87) | S | |||||
| CB (FICI = 1.09) | Ad | ||||||
| CB (FICI = 1.16) | A | ||||||
| Chloramphenicol | CB (FICI = 0.32–0.87) | S | |||||
| CB (FICI = 0.98–1.09) | Ad | ||||||
| Savory EO | Saturejae herba (Satureja kitaibelii Wierzb. ex Heuff., Lamiaceae, Savory) | Geraniol (50.4%) | ATCC 700603 | Chloramphenicol | CB (FICI = 0.21–0.43) | S | [60] |
| CB (FICI = 0.54–0.98) | Ad | ||||||
| CB (FICI = 1.09) | I | ||||||
| Tetracycline | CB (FICI = 0.43) | S | |||||
| CB (FICI = 0.56–0.98) | Ad | ||||||
| CB (FICI = 1.09) | I | ||||||
| Thyme EO | Thymi herba (Thymus saturejoides Coss., Lamiaceae, Azoukni) | Carvacrol (25.3%) Borneol (19.7%) |
Clinical isolate | Cefixime | CB (FICI = 0.75) | PS | [76] |
| Carvacrol (26.5%) Borneol (20.1%) |
CB (FICI = 0.75) | PS | |||||
| Carvacrol (45.3%) Borneol (7.5%) |
CB (FICI = 0.50) | S | |||||
| 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%) |
CIP 8291 | Amoxicillin | CB (FICI = 0.8) | PS | [75] |
| Tea tree EO | Melaleucae folium (Melaleuca alternifolia, (Maiden. and Betch.) Chee., Myrtaceae, Tea tree) | - | NCTC 9633 | Ciprofloxacin | CB (FICI = 0.73–0.95) | S | [2] |
| CB (FICI = 1.03–1.85) | A | ||||||
| Geraniol | - | ATCC 700603 | Chloramphenicol | CB (FICI = 0.32–0.87) | S | [60] | |
| CB (FICI = 0.98–1.09) | Ad | ||||||
| Tetracycline | CB (FICI = 0.76–0.80) | S | |||||
| CB (FICI = 0.95–1.10) | Ad | ||||||
| CB (FICI = 1.25–1.66) | A | ||||||
A: antagonism; Ad: addition; I: indifference; PS: partial synergy; S: synergy; CB: checkerboard assay; FICI: fractional inhibitory concentration index.