Use of lysostaphin to remove cell-adherent staphylococci during in vitro assays of phagocyte function.

Lysostaphin, a bacteriolytic enzyme, has been used to remove cell-adherent and extracellular Staphylococcus aureus from phagocyte-bacterial mixtures in vitro. Lysostaphin kills S. aureus more rapidly than penicillin, is not toxic for phagocytic cells and, when used for short periods at low concentrations, appears to enter neither human nor mouse mononuclear phagocytes. The use of lysostaphin provides the basis of a simple reliable direct in vitro assay for measuring the attachment and ingestion of S. aureus by phagocytic cells.