Cinnamomum zeylanicum, Dichrostachys glomerata and three other plants had anti-staphylococcal and antibiotic-modifying activity against drug-resistant phenotypes

Abstract

Background: The increase resistance of Staphylococcus aureus clinically, propels the search of novel approaches to treat staphylococcal infections. This study aims to investigate the anti-staphylococcal activity and antibiotic-modulating effects of the methanol extracts of five Cameroonian dietary plants namely Cinnamomum zeylanicum, Fagara xanthoxyloides, Imperata cylindrica,  Dichrostachys glomerata, Pentadiplanara brazzeana against a panel of S. aureus strains.

Methods: The plant extracts were prepared by maceration in methanol. The activity of extracts and the reference antibiotic (Ciprofloxacin) was evaluated against 25 strains of S. aureus including antibiotic-resistant phenotypes, using the broth microdilution method, and minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) were determined.

Results: Ciprofloxacin displayed anti-staphylococcal activity against all tested strains whereas the five extracts had selective activities with recorded MIC values ranged between 256–2048 μg/mL. Cinnamomum zeylanicum leave’s extract had the highest activity, with MIC values observed on 23/25 bacteria (92%). The lowest MIC value (256 µg/mL) was recorded against MRSA4 with extracts of Fagara xanthoxyloides seeds and Dichrostachys glomerata fruits. The most active extracts displayed bactericidal effects (MBC/MIC≤ 4). Antibiotic-modulating activity was observed on more than 70% of the tested S. aureus strains after the combination of CHL and TET with above extracts (at MIC/2 and MIC/4).

Conclusions: The overall data obtained highlight the suitability of the tested extracts, mainly those of C. zeylanicum and D. glomerata alone as well as in combination with chloramphenicol and tetracycline, as therapeutic agents for treatment of infections caused by resistant strains of S. aureus.