Effet antibactérien de l’extrait aqueux de l’écorce de Terminalia glaucescens Planch ex Benth (Combretaceae) sur la croissance in vitro des entérobactéries productrices de bêta-lactamases à spectre élargi (EBLSE)

Les bacteries productrices de beta-lactamases a spectre elargi sont responsables des echecs therapeutiques a infection bacterienne. Cette etude vise a evaluer les effets antibacteriens de lfextrait aqueux du macere d'fecorce de tige de Terminalia glaucescens Planch ex Benth (Combretaceae) sur huit enterobacteries productrices de beta-lactamases a spectre elargi (EBLSE) et deux souches de reference de Escherichia coliATCC. Les methodes de diffusion et de dilution sur Muller-Hinton ont permis dfevaluer l'factivite antibacterienne de l'fextrait. L'factivite  antibacterienne in vitro de l'fextrait aqueux de l'fecorce de tige de T.glaucescens est plus elevee que celle de la ceftriaxone (30 µg) et de la cefotaxime (30 µg) vis-a-vis des souches bacteriennes. Toutes ces souches sont resistantes aux deux antibiotiques, a l''fexception de celles de E. coli ATCC 25922 et 35218. L'fextrait aqueux de T. glaucescens est actif sur les 10 souches. Les zones d'finhibition a 200 mg/ml sont comprises entre 13±0,6 a 19,3±0,6 mm. Les CMI de l'extrait aqueux varient de 1,56 a 50 mg/ml. L'fextrait est bactericide sur toutes les souches apres 24 et 48 heures d'fincubation. Cette etude a montre que l'extrait de T. glaucescens pourrait etre utilise dans le traitement des maladies infectieuses.Mots cles: Terminalia glaucescens, extrait aqueux, activite antibacterienne

Contrasting the distribution of phenotypic and molecular variation in the freshwater snail Biomphalaria pfeifferi, the intermediate host of Schistosoma mansoni

Population differentiation was investigated by confronting phenotypic and molecular variation in the highly selfing freshwater snail Biomphalaria pfeifferi, the intermediate host of Schistosoma mansoni. We sampled seven natural populations separated by a few kilometers, and characterized by different habitat regimes (permanent/temporary) and openness (open/closed). A genetic analysis based on five microsatellite markers confirms that B. pfeifferi is a selfer (s≈0.9) and exhibits limited variation within populations. Most pairwise FST were significant indicating marked population structure, though no isolation by distance was detected. Families from the seven populations were monitored under laboratory conditions over two generations (G1 and G2), allowing to record several life-history traits, including growth, fecundity and survival, over 25 weeks. Marked differences were detected among populations for traits expressed early in the life cycle (up to sexual maturity). Age and size at first reproduction had high heritability values, but such a trend was not found for early reproductive traits. In most populations, G1 snails matured later and at a larger size than G2 individuals. Individuals from permanent habitats matured at a smaller size and were more fecund than those from temporary habitats. The mean phenotypic differentiation over all populations (QST) was lower than the mean genetic differentiation (FST), suggesting stabilizing selection. However, no difference was detected between QST and FST for both habitat regime and habitat openness