Etude de la résistance bactérienne aux antibiotiques induite par quelques extraits de plantes médicinales

Abstract

Many plants are used in Cameroon in the form of decoctions from a mixture of plants or macerates in order to treat people with typhoid fever or skin diseases. Yet in this country where modern medicine and traditional medicine are used, it is not uncommon to see many therapeutic failures of modern medicine after treatment by traditional medicine. Therefore, the present work aimed to elucidate the influence of the exposure of Salmonella enterica serotype Typhi (S.Typhi) and Staphylococcus aureus (S. aureus) to plant extracts used in the traditional pharmacopoeia on their ability to acquire resistance to antibacterial substances. According to the informations obtained from traditional medicine healers, several medicinal plants from different parts were selected to compose mixtures which were used to produce the plant extracts by decoction and by maceration. The susceptibility tests of S. Typhi and S. aureus to the various antibacterials were carried out. The different bacteria were exposed to plant extracts at a fixed concentration (0.5 mg/mL) contained in a nutrient broth renewed every 24 hours for 14 days. Subsequently, these bacteria were cultivated in a new nutrient broth without plant extract and renewed every 24 hours for an additional 14 days. An antibiogram was performed every 48 hours. Five antibiotic target genes (blaTEM, blaSHV, sul1, floR, and int1) were sought in S. Typhi after its exposure to plant extracts in order to detect their expression. The values of the diameters of the inhibition and of the MICs showed that the strains of S. Typhi and of S. aureus used in this work are susceptible as well to the antibiotics as to the extracts of plants tested. In addition, the two bacterial strains (S. Typhi and S. aureus) subjected to molecular pressure from plant extracts have acquired resistance to the antibiotics and plant substances tested. The detection of activity target genes (sul1, floR and int1) in S. Typhi after its exposure to plant extracts (Annickia chlorantha and Irvingia gabonensis) has shown the involvement of plant extracts in the expression of certain genes in course of bacterial resistance to antibiotics. This study shows that the exposure of bacteria to plant extracts induces their resistance to antibacterial substances by various mechanisms that may involve certain specific genes. Thus, antibacterial resistance, which is a major public health problem today, is not only the result of the uncontrolled use of antibiotics, but it is also the result of the bad use of plant extracts.