In the hospital, a large proportion of bacteraemia and implantable medical device infections are caused by Staphylococcus epidermidis. This microorganism is the most abundant on human skin and all patients are carriers. Its remarkable ability to form biofilms on most materials explains that catheter-related infections are by far the most common.~S. epidermidis infections are difficult to treat because most strains are multi-resistant and antibiotics are less effective in the presence of biofilms.~In addition, S. epidermidis poses a major diagnostic problem because it is also the first source of contamination of blood culture sample and intraoperative samples (in case of suspected infection of orthopedic material in particular). Thus, when a sample is positive for S. epidermidis, there is less than a 25% chance that it reflects true bacteremia in the patient and 30% of patients would inappropriately receive vancomycin following contaminated blood cultures. Differentiating a contamination of a blood or intraoperative sample from true S. epidermidis infection is therefore crucial for patient management because unnecessary antibiotic therapy is potentially responsible for the emergence of resistant strains, toxicity and additional costs.~The objective of this study is to identify the genetic markers that make it possible to differentiate the strains causing infections from the strains causing contamination by comparing their genomes using high throughput sequencing.
The purpose of the study is to identify biomarkers allowing the distinction between invasive and non-invasive strains of Staphylococcus epidermidis. This distinction is important to determine if the patient is infected and, as a consequence, if an antibiotic treatment is required.