Reduction of wall degradability of clindamycin-treated staphylococci within macrophages.

Clindamycin treatment of Staphylococcus aureus caused a remarkable thickening of the bacterial cell wall and made the bacterial wall much more resistant against lytic enzymes within bone marrow-derived macrophages as revealed by electron microscopy and radiolabeling experiments. This reduced wall degradability resulted from an increased number of O-acetyl groups in the murein. Furthermore, such clindamycin-treated bacteria were ingested by adherent bone marrow-derived macrophages at a higher rate than untreated bacteria. The medical aspects of these results are discussed.