Characterisation of a new bacteriophage infecting Staphylococcus epidermidis

Details

Supervisors

Gillis, Annika

Faculty

Faculté des bioingénieurs

Degree label

Master [120] : bioingénieur en sciences agronomiques, à finalité spécialisée

Abstract

enBacteriophages, or phages, are natural viruses capable of destroying bacteria and are currently attracting growing interest in the context of antimicrobial resistance. Among the applications envisaged, their use in biocontrol or for therapeutic purposes against multi-resistant bacteria appears particularly promising. This dissertation is part of this process and focuses on the characterisation of bacteriophage Stinkis, isolated for its lytic activity against a strain of Staphylococcus epidermidis, a commensal bacterium of the human skin, sometimes implicated in opportunistic infections. This work focused on several aspects of the biology of the bacteriophage Stinkis. Firstly, its stability was assessed at different temperatures and at different pH levels: results show a stability up to 50°C and from pH 5 to pH 9. The bacteriophage's lytic efficacy was measured using killing assays to observe the dynamics of bacterial destruction over time. In addition, the host range of Stinkis was determined by testing its ability to infect 50 strains of coagulase-positive (CoPS) and coagulase-negative staphylococci (CoNS), revealing a probable specificity for the bacterial surface receptors of this second group. An adsorption assay was used to quantify the speed and efficiency of the phage's attachment to its hosts in the presence and absence of divalent cations, while a one-step growth curve revealed a post infection multiplication capacity well above normal values. The results obtained in this study show that the bacteriophage Stinkis exhibits suitable stability, interesting lytic efficacy and a surprising ability to multiply. These properties suggest a potential application in the fight against the development of bacterial resistance against antimicrobials. Finally, this study paves the way for further investigations, in particular in-depth analysis of the bacteriophage genome and evaluation of its efficacy on biofilm models, in order to gain a better understanding of its interactions with S. epidermidis and envisage concrete applications in the future.