Antibiotics and their interaction with the host defense system in vivo

The Authors review their own data on the in-vitro effect of a wide number of chemotherapeutic agents on phagocyte functions (chemotaxis, phagocytosis, phagocytosis-dependent metabolic activation, microbicidal activity). Aminoglycosides affected some leukocyte functions only at concentrations higher than those achieved in therapy. Macrolides, glycopeptides and fluoroquinolones showed no toxic effect on phagocytic activities. Beta-lactams, generally, did not influence phagocytic activities. However, ceftriaxone and cefoperazone irreversibly inhibited neutrophil chemotaxis. Cefodizime, on the other hand, enhanced phagocytosis of both neutrophils and monocytes, when non-opsonized particles were used as phagocytic challenge. Rifamycins inhibited neutrophil chemotaxis and enhanced the intracellular killing of S. aureus. These interactions with phagocyte function were tested ex vivo on cells of normal volunteers treated with these antibiotics. While no effect on chemotaxis in subjects treated with ceftriaxone and cefoperazone could be demonstrated, both cefodizime and rifampicin maintained their in-vitro activity in ex-vivo experiences. These findings seem to indicate that, so far, no definite conclusion can be drawn on the in-vivo significance of in-vitro findings.