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).