Utilisation des métabolites extracellulaires des Pseudomonas fluorescents dans la lutte contre les Staphylococcus à coagulase négative.

Abstract

Coagulase-negative Staphylococci (CoNS), particularly Staphylococcus epidermidis, are harmless to human body. However, the immunodeficiency in the host or the colonization of foreign material inside the body by this bacterial group transforms these skin commensals into virulent forms. In this case, these bacteria are found in blood or in biofilms adhered to foreign material. To face the resistance of these forms to treatment and failures in the elimination of these pathogens, it has become necessary to find effective therapeutic agents. After confirming that the CoNS isolates have certain characteristics of this group and based on other studies cited in the literature, we selected 29 isolates of Pseudomonas from the roots of a wild grass plant (Rat barley = Hordeum murinum) for use in the inhibition of 20 CoNS isolates using the crossed streak method. The supernatants of Pseudomonas cultures in liquid MH medium were also tested. The best performing Pseudomonas PK isolate in CoNS inhibition has been identified by the API 20 NE system and used for the production of phenazinic compounds. It was inoculated into the liquid NBY medium and then solvent extraction by ethyl acetate was carried out. The dry compound was used against CoNS isolates. The results of this study showed that the 29 Pseudomonas inhibited 19/20 Staphylococcus and that each Pseudomonas inhibited a group of CoNS. The larger inhibitory strain PK inhibited 14 CoNS isolates with inhibition zones ranging from 12 mm to 55 mm. The supernatants of Pseudomonas cultures in liquid MH medium showed no inhibitory effect, this is due to the low concentration of active substance in each supernatant. The dry extract phenazine compound inhibited 13 staphylococcal isolates with inhibition zones ranging from 6.5 to 28.5 mm. The analysis of the compound obtained by the UV-visible and the infrared spectrophotometers showed some characteristics that make the compound belong hydroxyphenazine.