Prévalence de la résistance aux antibiotiques des souches bactériennes cliniques et effet des extraits de plantes et des biomolécules microbiennes sur les souches multirésistantes

Abstract

Antibiotics, used to treat bacterial infections, are one of the most important advances in human medicine in the 20th century. However, this discovery has been accompanied by the emergence and spread of antibiotic-resistant strains. The main species of pathogenic bacteria found in hospital settings and in the community are mainly: Enterobacteriaceae producing extended-spectrum batalactamases ESBL, Gram-negative non-fermenting bacilli resistant to imipenem, and ceftazidim as well as Staphylococcus aureus resistant to méthicilline, the search for an alternative becomes more than necessary ; in order to combat this major health problem .In this context, the objective of this work is to demonstrate the antibacterial activity of the extracts of some medicinal plants ( Origanum glandulosum , Thymus vulgaris, Salvia officinalis, Pelargonium. Roseum , Rosemarinus officinalis and Menthe pulegium )and microbial biomolecules on reference and multi-resistant strains, and the search for molecules inhibiting the formation of biofilms. A total of 323 samples were perform, and 196 strains were collected over 3 months from various samples received at the central laboratory of the military regional university hospital of Constantine; the predominant bacterial group is mainly represented by Enterobacteriaceae producing extended-spectrum beta-lactamases (E-BLSEs) with a level of (27.47%) and marked resistance to betalactams (Ampicillin: 100%, Amoxicillin 100% and Amoxicillin –clavulanate ) . A significant resistance against quinolones and aminosides were also observed , concerning the strains of P. aeruginosa and A. baumannii resistance to antibiotics include carboxypenicillins,ureidopenicillins,cephalosporins, and even carbapenems . Hydrodistillation of the aerial parts of the 6 species of medicinal plants (Origanum glandulosum Thymus vulgaris , Salvia officinalis Pelargonium .roseum , Rosemarinus officinalis and Menthe pulegium) gave essential oil (EO) yieldes range from 0.5 to 2.09% (m/m).Preliminary evaluation of antibacterial activity allowed us to select the most active EOs :O.glandulosum, T.vulgaris and S. officinalis . Gas chromatography coupled to mass spectrometry (GC/MS) allowed the identification of 9 compounds for oregano EO and thyme EO , and 14 compounds for sage EO ; oregano essential oil was characterized by thymol richness (49.52); while thyme and sage EO, the major chemical compounds were represented by borneol (76.42%) and camphor (39.62%) respectively. In order to maintain the stability of the EO against certain environmental factors, the encapsulation of EO oregano was carried out by high-speed homogenization (HSH) in nanocapsules and by high-pressure homogenization (HPH) in nanoemulsion, both formulations exhibited relatively significant activity against the sessile form and in the biofilm state at sub-inhibitory concentrations. The investigation of bacterial antagonism by Lb. plantarum strains in the solid medium was carried out by the double layer method and diffusion in the well .This study made it possible to demonstrate the frequency and level of resistance of the MDR strains in a hospital environment, the results obtained suggest that the EOs, in particular the EO of oregano, could be used in the prevention and treatment of bacterial infections.