Anti-Klebsiella and antibiotic-potentiation activities of the methanol extracts of seven Cameroonian dietary plants against multidrug-resistant phenotypes over-expressing AcrAB-TolC efflux pumps

Background: Bacterial infections continue to wreak havoc around the world with high death rates. African medicinal plants and the phytoconstituents showed high efficiency in impeding the growth of the resistance phenotypes of bacteria The present work was designed to determine the antibacterial activity of seven Cameroonian dietary plants against clinical MDR isolated of Klebsiella sp. These plants included Persea americana Miller (Lauraceae), Psidium guajava Linn. (Myrtaceae), Mangifera indica Linn. (Anacardiaceae), Citrus sinensis Linn. (Rutaceae), Passiflora edulis Sims (Passifloraceae), Garcinia kola Heckel (Guttiferae), and Artocarpus heterophylus Lam. (Moraceae). Methods: Minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) determinations on the used bacterial strains alone, in the presence of an efflux pump inhibitor, phenylalanine arginine beta naphthylamide (PAβN), and in combination with antibiotics, were performed by the microbroth dilution method using a rapid colorimetric para-Iodonitrotetrazolium chloride (INT) assay. Results: The tested botanicals had different extend of antibacterial activities, with MIC ranges of between 256 μg/mL and 2048 μg/mL. Botanicals from Persea americana, Psidium guajava, Mangifera indica, Artocarpus heterophyllus, and Garcinia kola bark had detected MIC values on all 15 tested Klebsiella strains. PAβN potentiated the activity of the botanicals on all tested bacteria, with the increase of activity ranging from 4 to more than 128-fold. The most significant increase of 4 to more than 128-fold was observed with botanicals from leaves and bark of Psidium guajava and Mangifera indica. The botanicals from the leaves of Mangifera indica potentiated the activity of eight out of ten tested antibiotics (Ceftriaxone, Chloramphenicol, Levofloxacin, Ampicillin, Tetracycline, Imipenem, Doxycycline, and Levofloxacin) against 100% of the tested bacteria. Conclusion: In the present study, it was demonstrated that botanicals from Persea Americana, Psidium guajava, Mangifera indica, Artocarpus heterophyllus, and Garcinia kola had the highest spectrum of activity, and can be used to combat the resistance of Klebsiella species