Inhibitory Effect of Methanolic and Methanolic-Aqueous Mixture Extract of Leaves of Plectranthus neochilus Schltr (Lamiaceae) and Bauhinia rufescens Lam (Fabaceae) on Two Strains of Enterobacteria Producing Beta-lactamases

Abstract

The objective of the study was to evaluate in vitro inhibitory effect of methanolic and methanolic-aqueous mixture extracts of Plectranthus neochilus Schltr (P. neochilus) and Bauhinia rufescens Lam (B. rufescens) on the growth of Escherichia coli 25922 and Proteus mirabilis. A phytochemical screening was carried out to highlight compounds (phenolic compounds, flavonoids, alkaloids) with antibacterial activity. Then, an antibiogram was Carried out to investigate the enzymes rendering the resistance. Finally, the E-test was used to evaluate the antibacterial activity of the extract mixture. The Screening results showed that both plants contain total phenolics, flavonoids and alkaloids compounds. The antibiogram has made it possible to establish the sensitivity profile of the strains tested with regard to certain antibiotics. The extract mixture showed antibacterial activity on both strains tested. In the present work, the different mixtures of extracts showed an inhibitory effect on Escherichia coli 25922 [a strain sensitive to almost all the antibiotics tested, in particular the three classes: beta-lactams (Ceftazidine, Ceftriaxone, Meropenem), quinolones (Levofloxacin, Ciprofloxacin) and aminoglycosides (Gentamicin, Amikacin)] and on Proteus mirabilis (a multiresistant strain with almost all the antibiotics tested).

Antimicrobial Properties of the Hydroethanolic Extract of <i>Bauhinia rufescens</i> L. and <i>Euphorbia hirta</i> L., Two Plants of the Traditional Chadian Pharmacopoeia

“…The hospital strain of Staphylococcus aureus and the reference strain (Staphylococcus aureus ATCC 25922) were all sensitive to the hydroethanolic extract of Bauhinia rufescens with a MIC of 12.5 mg/ml. Other work has also highlighted the sensitivity of Staphylococcus aureus to Bauhinia rufescens extracts with MICs varying according to the nature of the solvent used and my extraction method (14,10,5).…”

“…For hospital strains the MIC varies from 25 to 50 mg/ml depending on the part of the plant used. Many studies carried out throughout the world have confirmed the sensitivity of Escherichia coli to extracts of Bauhinia rufescens and Euphorbia hirta [3,15,13,14,10,5].…”