Combinatory in vitro effect of plant extracts with antibiotics on multi-resistant bacteria

Antimicrobial resistance is recognized as one of the major health challenges. Thus, urgent therapeutic solutions are needed. This study aims to test the activity of plant extracts against multi-resistant bacteria, as well as the synergistic effect of these extracts with some antibiotics.

The evaluation of the antibacterial effect of eight medicinal extract plants (G. alypum, R. graveolens, U. dioica, P. lentiscus, A. vulgaris, L. angustifolia, T. vulgaris, and J. phoenicea) against 10 bacterial strains (K. pneumoniae, E. coli, C. freundii, S. haemolyticus, S. epidermidis, S. saprophyticus) has been performed using both wells and disks diffusion methods (DDM/WDM). The evaluation of the synergistic effect of some of the natural extracts with some antibiotics has been performed using the disk diffusion method (DDM).

A significant difference resulting from the effect of various plant extracts on different bacterial species has been observed. Interestingly, an important inhibition zone related to the effect of the essential oil of T. vulgaris and L. angustifolia was observed in all bacterial strains. The combination of plants/antibiotics does not always give a more effective effect than the antibiotic /or the plant extract alone. The lavender oil seems to be able to enhance the activity of ertapenem on C. freundii, while the combination of A. vulgaris/ertapenem induced the reduction of the inhibition zone on the same species.

These results are of great importance; regarding the valorization of natural resources for the creation of solutions to urgent health problems while taking advantage of existing pharmaceutical resources.