Cefotaxime: rate of bacterial killing and interactions with serum and leukocyte activity.

Cefotaxime (HR 756) was compared with cefazolin and cephaloridine with regard to the rate of bacterial killing and to the influence on the bactericidal activity of human serum and polyrnorphonuclear leukocytes. At concentrations equal to 1-2 x MIC cefotaxime showed a more rapid and complete bactericidal activity on E. coil K 12 than cephaloridine and cefazolin. In presence of the latters in fact, bacterial regrowth was observed after 24 hours. On S. aureus a complete killing activity of cefotaxime appeared at concentrations of 8 x MIC. A synergism seemed to exist between the complement dependent bactericidal activity of normal human serum and cephalosporins. E. coil K 12 (a rough strain) was killed by the combi nation of human serum and both cefotaxime and cefazolin at concentrations that were not bactericidal by themselves. Cephaloridine on the contrary showed an additive activity with normal human serum. Finally evidence that cefotaxime enhanced the bactericidal activity of human polymorphonuclear leukocytes against S. faecaiis, is reported.