title: Cidal activity of oral third-generation cephalosporins against Streptococcus pneumoniae in relation to cefotaxime intrinsic activity.
abstract: This study explores the killing kinetics within 12 h of four oral third-generation cephalosporins against ten Streptococcus pneumoniae strains exhibiting cefotaxime minimum inhibitory concentrations (MICs) from 0.03 to 2 microg/ml. Killing curves were performed with concentrations achievable in serum after standard doses (0.015-4 microg/ml). Reductions of 90% were achieved with all compounds at serum-achievable concentrations for strains exhibiting cefotaxime MIC < or = 0.5 microg/ml. Against strains with cefotaxime MIC > or = 1 microg/ml, only cefditoren reached a 90% reduction with concentrations of 0.5-1 microg/ml doses. At 4 microg/ml, cefditoren and cefotaxime reached 99.9% reduction in seven of the ten strains studied. At serum-achievable concentrations, cefdinir and cefixime were not bactericidal against strains exhibiting cefotaxime MIC > or = 0.25 microg/ml and > or = 0.5 microg/ml, respectively. Cefditoren showed the best killing kinetic profiles and this observation may be important when choosing an oral third-generation cephalosporin as initial or sequential therapy.
authors.affiliation: Microbiology Department, School of Medicine, Universidad Complutense de Madrid, Avda. Complutense s/n, 28040, Madrid, Spain.
authors.forename: F
authors.initials: F
authors.lastname: Cafini
authors.forename: L
authors.initials: L
authors.lastname: Aguilar
authors.forename: L
authors.initials: L
authors.lastname: Alou
authors.forename: M J
authors.initials: MJ
authors.lastname: Giménez
authors.forename: D
authors.initials: D
authors.lastname: Sevillano
authors.forename: M
authors.initials: M
authors.lastname: Torrico
authors.forename: N
authors.initials: N
authors.lastname: González
authors.forename: J J
authors.initials: JJ
authors.lastname: Granizo
authors.forename: J E
authors.initials: JE
authors.lastname: Martín-Herrero
authors.forename: J
authors.initials: J
authors.lastname: Prieto
mesh_terms: D000900:Anti-Bacterial Agents / Q000494:pharmacology*; D000077525:Cefdinir; D002439:Cefotaxime / Q000494:pharmacology*; D002511:Cephalosporins / Q000494:pharmacology; D008826:Microbial Sensitivity Tests; D013296:Streptococcus pneumoniae / Q000187:drug effects*
chemical_list: D000900:Anti-Bacterial Agents; D002511:Cephalosporins; D000077525:Cefdinir; D002439:Cefotaxime