Résumé:
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.
