title: Activity of cefotaxime and ceftriaxone alone and in combination with penicillin, ampicillin and piperacillin against neonatal meningitis pathogens.
abstract: The activities of penicillin G, ampicillin, piperacillin, cefotaxime and ceftriaxone alone and in combination against 130 isolates of Escherichia coli, group B streptococci and Listeria monocytogenes from neonatal meningitis were assessed by using agar dilution, checkerboard and time-kill techniques. Cefotaxime and ceftriaxone were highly active against E. coli and group B streptococci (MIC90 0.05-0.1 mg/1) but not active against List. monocytogenes. Penicillin G was more active than ampicillin and piperacillin against group B streptococci (MIC90 0.1, 0.12 and 0.24 mg/l respectively) and ampicillin was the most active against List. monocytogenes (MIC90 0.6 mg/l). Every double beta-lactam combination was synergistic for 3-14% of E. coli, 8-26% of group B streptococci and 67-100% of List. monocytogenes in the checkerboard titration. The ceftriaxone combinations were less synergistic than the cefotaxime combinations. In time-kill evaluations using concentrations representative for cerebrospinal fluid, the killing kinetics of E. coli were not influenced by any combination. A significant delay in killing of group B streptococci was observed with penicillin G-cephalosporin and ampicillin-cephalosporin combinations. A significant increased killing of List. monocytogenes was observed with penicillin G-cephalosporin combinations. The other combinations did not alter the killing kinetics of group B streptococci and List. monocytogenes.
mesh_terms: D000667:Ampicillin / Q000494:pharmacology*; D002439:Cefotaxime / Q000494:pharmacology*; D002443:Ceftriaxone / Q000494:pharmacology*; D004338:Drug Combinations; D004347:Drug Interactions; D004926:Escherichia coli / Q000187:drug effects; D006801:Humans; D007231:Infant, Newborn; D008089:Listeria monocytogenes / Q000187:drug effects; D008581:Meningitis / Q000382:microbiology*; D008826:Microbial Sensitivity Tests; D010406:Penicillins / Q000494:pharmacology*; D010878:Piperacillin / Q000494:pharmacology*; D013292:Streptococcus agalactiae / Q000187:drug effects
chemical_list: D004338:Drug Combinations; D010406:Penicillins; D002443:Ceftriaxone; D000667:Ampicillin; D002439:Cefotaxime; D010878:Piperacillin