Increasing antibiotic activity against a multidrug-resistantAcinetobacterspp by essential oils ofCitrus limonandCinnamomum zeylanicum

Abstract

The genus Acinetobacter has gained importance in recent years due to involvement in serious infections and antimicrobial resistance. Many plants have been evaluated not only for direct antimicrobial activity, but also as resistance modifying agents. The Essential oil of Citrus limon (EOCL) addition at 156.25 µgmL(-1) (MIC/8) sub-inhibitory concentration in the growth medium led to MIC decrease for amikacin, imipenem and meropenem. The Essential oil of Cinnamomum zeylanicum (EOCZ) addition at 78.125 µg mL(-1) (MIC/8) sub-inhibitory concentrations in the growth medium caused drastic MIC reduction of amikacin. Results of combining antibiotics and essential oils had shown us a synergistic effect with both essential oils/amikacin combinations. An additive effect was observed with the combinations of both essential oils and gentamicin. The results of this study suggest that essential oil of C. limon and C. zeylanicum may suppress the growth of Acinetobacter species and could be a source of metabolites with antibacterial modifying activity.

Antimicrobial synergism and cytotoxic properties of Citrus limon L., Piper nigrum L. and Melaleuca alternifolia (Maiden and Betche) Cheel essential oils

“…The mixture of C. limon and P. nigrum EOs exhibited the strongest synergism with the same FICI value of 0.06 against both tested pathogens, S. mutans and C. albicans , while the other two combinations expressed also efficiency but quite less; the FICI values for combination C. limon and M. alternifolia were 0.24 and 0.12, while those for the P. nigrum and M. alternifolia , 0.39 and 0.34, against S. mutans and C. albicans , respectively. Synergism in activity between these EOs has been also confirmed in some other studies . The major EO constituents with their different functional groups, when applied in combination, are capable to achieve stronger activity; this phenomena is known as ‘vertical synergy’ .…”

Essential Oils and Their Components as Modulators of Antibiotic Activity against Gram-Negative Bacteria

“…Cinnamon ( Cinnamomum zeylanicum Nees., Lauraceae) and lemon ( Citrus limon L. Burm. F., Rutaceae) EOs showed strong synergistic effects in combination with amikacin against a multidrug-resistant A. baumannii clinical isolate (A-06 strain) [40]. The study provides no information on the chemical composition of both cinnamon and lemon EOs.…”

Comparative in vitro efficacy of eight essential oils as antibacterial agents against pathogenic bacteria isolated from pet-turtles

“…The highest MIC, 0.25%, was observed for A. dhakensis and A. hydrophila while the other species had a similar MIC profile. Cinnamon oil has also been reported to restrain the growth of many Grampositive and Gram-negative bacteria, some of which are multidrug-resistant (Keskin and Toroglu 2011;Guerra et al 2012;Al-Mariri and Safi 2014). Cinnamaldehyde is the major component of cinnamon oil; it can exert different antibacterial activities depending on the concentration applied and is Citrobacter freundii capable of altering the lipid profile of the microbial cell membrane (Wendakoon and Sakaguchi 1995;Nazzaro et al 2013).…”