Abstract

EXTRACTS FROM Acmella caulirhiza POTENTIATE THE ACTIVITY OF CIPROFLOXACIN AGAINST MULTIDRUGRESISTANT BACTERIA EXPRESSING EXTENDED-SPECTRUM BETA-LACTAMASES

Matchuenkam Gayap Sonia Raissa, Fotsing Kwetche Pierre René*, Mafo Fokam Marcelle Aude, Yawat Djogang Anselme Michel, Munvera Mfifen Aristide, Dzotam Tamgue Joachim, Fonkeng Sama Léonard, Kuiate Jules Roger

Abstract

Faced with the disturbing phenomenon of bacterial resistance, the search for new efficient and available natural antibacterial agents becomes primordial. In the present study we assessed the antibacterial potential of four extracts (hexane, methylene chloride, ethyl acetate and ethanol) from Acmella caulirhiza (a plant that belongs to the Asteraceae family) in restoring the activity of three common antibiotics on multidrug-resistant and extended spectrum betalactamase- positive bacteria. Extracts were primarily subjected to chemical screening according to standard protocols. The minimal inhibitory concentration (MIC) and minimal bactericidal concentration (MBC) tests were conducted with a modified rapid piodonitrotetrazolium chloride (INT) colorimetric assay. Subsequently, association tests were performed between these extracts and two beta-lactams (Amoxicillin, Ampicillin) on one hand and a fluoroquinolone (Ciprofloxacin) on the other. The phytochemical assays revealed that all crude extracts contained alkaloids, triterpenes and sterols. The ethyl acetate and ethanol extracts further contained all secondary metabolites investigated. Only the hexane extract displayed moderate activity on multidrug-resistant strains (Klebsiella pneumoniae, Klebsiella oxytoca and Serratia odorifera) with the MIC values found between 512 and 1024 μg/mL. After combination, improved amoxicillin activity was observed with all extracts though this was observed on a single clinical isolate (Staphylococcus spp.). Ciprofloxacin was potentiated on 5 out of 7 (71.43%) multidrug-resistant isolates by all the extracts, including those that did not have any activity when they were tested alone (FIC values: 0.125 through 0.5). These findings suggested that the extracts might contained inhibitors which act on other resistance mechanisms like efflux pumps. In addition, it appeared that constituents that are responsible for the antibacterial activity of the extracts when they were used alone are not the ones that induced the synergistic effects once used in combination. It might be legitimate to pay more attention on these combinations, especially in the caretaking of infections due to extended-spectrum β-lactamases-positive bacteria which also express resistance to Ciprofloxacin.

Keywords: Acmella caulirhiza, multidrug-resistance, extended spectrum beta-lactamase, ciprofloxacin.