Characterization of a neutrophil-inhibitory factor from clinically significant Staphylococcus epidermidis

Sixteen isolates of Staphylococcus epidermidis recovered from blood cultures of patients were examined for ability to adhere to plastic tubes, for agglutinability with concanavalin A, and for the ability to inhibit the bactericidal activity of neutrophils collected from healthy human volunteers. Neutrophil inhibition was induced by six of nine isolates associated with clinically significant infections but by only one of seven clinically defined as blood contaminants (P = .05). Six of the eight significant bacteremic episodes were associated with neutrophil-inhibitory isolates (P = .03). Neutrophil inhibition was independent of either adherence or ConA agglutination. Neutrophil inhibition may represent an independent virulence factor associated with Staphylococcus epidermidis.