Coagulase-negative staphylococci (CoNS) are the most frequent constituent of the normal flora of the skin. These organisms can be agents of clinically significant infection but are also common contaminants in clinical specimens.
Staphylococcus epidermidis accounts for more than half of staphylococci isolated from human skin and more than 75 percent of CoNS in clinical specimens. Other clinically significant species include S. saprophyticus and S. lugdunensis.
Use of intravascular devices is an important contributor to bloodstream infections with CoNS. Coagulase-negative staphylococci account for approximately one-third of bloodstream isolates in intensive care units, making these organisms the most common cause of nosocomial bloodstream infection.
Among patients with blood cultures positive for CoNS, approximately 12 to 25 percent have significant bloodstream infection. Distinction between contamination and true infection is important for clinical management.
Species identification may be approached based on a combination of morphologic assessment, biochemical and metabolic testing, and antibiotic susceptibility results.
Clinical manifestations include fever, hypotension, and leukocytosis. Microbiologic factors include growth in culture within 48 hours, growth in both aerobic and anaerobic bottles, and multiple cultures (two or more blood culture sets) positive for the same organism with identical antibiograms.
CoNS possess determinants that facilitate survival on skin surfaces, biofilm formation, adhesion to tissue and prosthetic surfaces, and components involved in immune evasion.
Complete genome sequence of USA300, an epidemic clone of community-acquired meticillin-resistant Staphylococcus aureus. - PubMed - NCBI
Staphylococcus epidermidis Esp inhibits Staphylococcus aureus biofilm formation and nasal colonization. - PubMed - NCBI