Clindamycin and its action on the susceptibility of pathogenic bacteria to phagocytosis.

The role of various surface virulence factors in bacterial resistance to opsonophagocytosis has been investigated in relation to the effect of clindamycin at concentrations below those which inhibit growth (sub-MIC). In each case studied (Streptococcus pyogenes, Staphylococcus aureus and Bacteroides fragilis) contact with the drug under these conditions potentiated complement-mediated opsonization of the bacterial cells resulting in a greater and more rapid deposition of C3 as C3b on the cell surface. Several other features of the phagocytic process were enhanced in consequence.