Phenotypic and Genotypic Assays to Evaluate Coagulase-Negative Staphylococci Biofilm Production in Bloodstream Infections

Coagulase-Negative Staphylococci (CoNS) are commensal on human body surfaces and for years, they were not considered a cause of bloodstream infection and were often regardered as contamination. However, the association of CoNS with nosocomial infection is increasingly recognized. The insertion of cannulas and intravascular catheters represents the first source of CoNS entry into the bloodstream, causing bacteremia and sepsis. They owe their pathogenic power to their ability to produce biofilms on surfaces, such as medical devices. In this study, we evaluate the adhesive capacity of CoNS isolated from blood cultures by comparing spectrophotometric phenotypic assay with genotypic analysis based on the evidence of the ica operon. We retrospectively reviewed the database of CoNS isolated from blood cultures, that were considered to be responsible for 361 bloodstream infections. Among them, we selected 89 ones who had full records. Our data show that S. epidermidis was the predominant species isolated, and with greater adhesive capacities, especially those with the complete operon. Knowing the adhesive capabilities of a microorganism responsible for sepsis can be useful in implementing appropriate corrective and preventive measures, as conventional antibiotic therapy cannot effectively eradicate biofilms.