ANTIBIOTIC EFFECTS ON BACTERIAL VIABILITY, TOXIN PRODUCTION, AND HOSTRESPONSE

The efficacy of an antibiotic in human or experimental infection is pr esumed to be proportional to its in vitro antimicrobial activity, yet antibiotics having comparable in vitro activity may have markedly diff erent efficacies in vivo. For example, we have reported that clindamyc in is more efficacious than penicillin in experimental gas gangrene ca used by Clostridium perfringens in animals. To explain these differenc es, we compared the dynamics of bacterial killing and suppression of t oxin synthesis. In addition, we investigated the ability of clindamyci n and penicillin to modulate lipopolysaccharide-induced cytokine produ ction in human peripheral blood mononuclear cells. Our results suggest that clindamycin affects protein synthesis in both prokaryotic and eu karyotic cells. These data may, in part, explain why the efficacy of c lindamycin is greater than that of penicillin and demonstrate that cli ndamycin may be an important immune modulator.