Interactions between antibiotics and phagocytosis in bacterial killing.

The interaction between antimicrobial agents and phagocytic killing can be studied using three different approaches. The first approach, which is probably the most clinically relevant, is to study intracellular penetration and bioactivity against microorganisms relevant to a particular subcellular 'sequestration' site. The second approach, as yet of uncertain clinical relevance, is to study the toxicological impact of antimicrobial agents on phagocytic functions. This approach has shown that the cell membrane is the target for many enhancing or depressing effects associated with amphotericin B, antimalarials, coumarines, rifampicin and semi-synthetic cephalosporins. Of probable clinical relevance, the third approach is to study the effect on the phagocytic function of preincubating the microorganism. Modification of opsonisation has been the most frequently recognized mechanism, although the release of activating substances and sensitization of the microorganism to oxygen-dependent or -independent killing mechanisms have been described.