Évaluation in vitro de l’activité antimicrobienne de quelques plantes médicinales camerounaises et étude de la cinétique d’activité de quelques antibiotiques usuels vis-à-vis des isolats cliniques de helicobacter pylori

Abstract

Bacterial infections continue to cause serious problems in the world. The search for new antimicrobial agents is of great necessity in view of the ever increasing pressure of the resistance of microorganisms against conventional antibiotics. This makes it imperative when seeking new drugs that could substitute those for which resistance phenomena have developed or restore their lost activity. It is in this context that the present study take place to evaluating the antimicrobial properties of nine Cameroonian medicinal plants against ten clinical isolates of Helicobacter pylori causative agent of gastroduodenal ulcers. Extracts of plant samples of the selected plants were prepared by maceration of the plant powder in ethyl acetate firstly and secondly in methanol. These were the following plants: Afzelia africana, Ageratum conyzoides, Crossopteryx febrifuga, Khaya senegalensis, Moringa oleifera, Piliostigma reticulatum, Acacia albida, Azadirachta indica and Picralima nitida. The antimicrobial activity of these plant extracts as well as that of Amoxicillin, Erythromycin, Metronidazole, Clarithromycin, Ciprofloxacin and Doxycycline; antibiotics used in treatment regimens for this infection were evaluated in ten clinical isolates of Helicobacter pylori by the microdilution method in liquid medium. Next, the kinetics of the bactericidal activity of Clarithromycin, Ciprofloxacin and Doxycycline against Helicobacter pylori was evaluated by counting method after culture on agar medium. Only certain methanolic plant extracts exhibited moderate antimicrobial activity compared to those extracted with ethyl acetate. The best activity anti-Helicobacter pylori obtained was that of methanol extracts of Acacia albida, Picralima nitida and Azadirachta indica against 30%, 50% and 10% of isolates tested with MIC value 256 μg/mL. However, extracts of Afzelia africana, Ageratum conyzoides, Crossopteryx febrifuga, Khaya senegalensis, Moringa oleifera and Piliostigma reticulatum showed no significant antimicrobial activity. Ciprofloxacin presented bactericidal time dependent activity contrary to that of Clarithromycin and Doxycicline was rather dependent on concentration.