Influence of Five Antianaerobic Antibiotics on Endotoxin Liberation by Gram-Negative Anaerobes

AbstractEndotoxin, a lipopolysaccharide (LPS), has for many years been recognized as a key effector molecule in the pathogenesis of Gram-negative sepsis and septic shock. Seven strains of the Bacteroides fragilis group were studied for their ability to liberate endotoxin upon exposure to five anti-anaerobic antibiotics, trovafloxacin, cefoxitin, imipenem, meropenem and piperacillin/tazobac-tam, in an in-vitro experiment. The minimum inhibitory concentrations (MICs) of the antibiotics were determined by using the broth macrodilution technique. Thereafter, endotoxin liberation was detected in the filtered broth cultures of the anaerobic bacteria by the limulus amebocyte lysate (LAL) assay after exposing the organisms to four different concentrations of the antibiotics in supplemented Brucella broth. Aliquots of the broth cultures were also taken at intervals of 0, 6, 24 and 48 h for viable counts. All seven Gram-negative anaerobic bacteria investigated liberated induced cell-free endotoxin in filtered broth...