In vitro activity of certain antimicrobial agents in combination with Augouardia letestii hexane extracts against methicillin-resistant Staphylococcus aureus

Abstract

The ability of methicillin-resistant Staphycoccus aureus to acquire resistance to most antibiotics is a worldwide concern that necessitated the study of the antimicrobial activity of the medicinal plant Augouardia lestestii alone and in combination with existing antibiotics. The minimum inhibitory concentration was determined by broth microdilution method and the evaluation of synergy was determined by the checkerboard dilution test. In this study, the antimicrobial activity of A. lestestii leaves, stem barks and roots were investigated against methicillin resistant S. aureus strains. The A. lestestii hexane fraction showed good antibacterial activity against all strains with minimum inhibitory concentration ranging from 125 to 250 μg/ml. Further, synergistic effects were observed for all antibiotics (ampicillin, norfloxacin, ciprofloxacin and erythromycin) except for nisin. The study also validated the traditional use of A. lestestii against infectious diseases.

Key words: Augouardia lestestii, antimicrobial activity, synergistic combinations, drug-resistance.