Cidal activity of oral third-generation cephalosporins against Streptococcus pneumoniae in relation to cefotaxime intrinsic activity.
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.
Cafini
F
F
Microbiology Department, School of Medicine, Universidad Complutense de Madrid, Avda. Complutense s/n, 28040, Madrid, Spain.
Aguilar
L
L
Alou
L
L
Giménez
M J
MJ
Sevillano
D
D
Torrico
M
M
González
N
N
Granizo
J J
JJ
Martín-Herrero
J E
JE
Prieto
J
J
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*
D000900:Anti-Bacterial Agents; D002511:Cephalosporins; D000077525:Cefdinir; D002439:Cefotaxime