Botanicals from nine selected Cameroonian edible plants displayed Anti-pseudomonas effects and potentiated the activities of antibiotics against multidrug-resistant phenotypes over-expressing MexAB-OprM efflux pumps

Abstract

Background: Despite the recognized efficiency of antibiotic therapy, the annual cases of deaths related to bacterial diseases is still growing in developing countries. In the present study, the in vitro antipseudomonal activity of the methanol extracts of nine food plants from Cameroon against the multidrug-resistant strains and isolates of Pseudomonas aeruginosa overexpressing active efflux pumps was determined. These plants included Persea americana, Syzygium jambos, Mangifera indica, Garcinia kola, Citrus sinensis, Passiflora edulis, Vernonia amygdalina, Aframomum letestuanum, and Artocarpus heterophylus. Methods: The liquid microplate dilution method using the rapid para-Iodonitrotetrazolium chloride (INT) colorimetric method was applied to evaluate the antipseudomonal activities of botanicals, as well as their association with the efflux pump inhibitor and antibiotics. Results: All botanicals displayed an antibacterial activity that varies from one bacterium to another, in the minimal inhibitory concentration (MIC) range of 64 µg/mL to 2048 µg/mL. The extracts from a mixture of leaves and bark of Syzygium jambos and Mangifera indica, the bark of Garcinia kola, and the leaves of Persea americana had the highest spectrum of antipseudomonal activity, with their inhibitory effects being noted in 100% of the 15 tested bacteria. Botanical from the leaves of Garcinia cola, were active against 90% of the strains tested, that from the bark of Persea americana and the leaves of Citrus sinensis were active against 70% and 60% of tested strains and isolates. Botanicals from the leaves and bark of Mangifera indica were very active against the isolates P124 and P57 with a MIC value of 64 µg/mL. At the concentration of MIC/2 and MIC/4, the extract from the leaves of Mangifera indica and Syzygium jambos potentiated the activity of four antibiotics (Penicillin, Ampicillin, Imipenem, Augmentin) on 100% (7/7) of the strains and isolates tested. Persea americana leaf extract also enhanced the activity of penicillin, tetracycline, chloramphenicol, levofloxacin, ampicillin, and augmentin in 85% (6/7) of strains and isolates tested. The activity of all tested antibiotics increased in the presence of botanicals against at least one bacterial strain. The extract of leaves and bark of Persea americana, Psidium guajava, and leaves of Syzygium jambos potentiated the activity of 80% of the antibiotics on the strains and isolates tested. Conclusion: Finally, the methanol extracts from the leaves and bark of Mangifera indica could be used effectively alone or in combination with antibiotics in the treatment of bacterial infection caused by Pseudomonas aeruginosa including antibiotic-resistant phenotypes expressing efflux pumps.