Sevillano Fernández, DavidAguilar, LorenzoAlou Cervera, LuisGiménez, María JoséGonzález Hidalgo, NataliaEcheverría, OlatzTorrico, MarthaValdes, LauraCoronel, PilarPrieto Prieto, José2024-07-292024-07-292008Sevillano D, Aguilar L, Alou L, Giménez MJ, González N, Echeverría O, Torrico M, Valdes L, Coronel P, Prieto J. Beta-lactam activity against penicillin-resistant Streptococcus pneumoniae strains exhibiting higher amoxicillin versus penicillin minimum inhibitory concentration values: an in vitro pharmacodynamic simulation. Chemotherapy. 2008;54(2):84-90.0009-315710.1159/000118659https://hdl.handle.net/20.500.14352/107152Background: Activity of simulated serum concentrations after oral therapy with 400 mg cefditoren pivoxil b.i.d., 500 mg cefuroxime axetil b.i.d. and 875/125 mg amoxicillin/clavulanic acid b.i.d. and t.i.d. regimens was explored over 24 h against Streptococcus pneumoniae.Methods: Computerized pharmacodynamic simulations were performed against strains with penicillin/amoxicillin/cefuroxime/cefditoren minimum inhibitory concentrations (MICs, µg/ml) and serotypes: strain 1 (0.25/0.12/1/0.12; serotype 6A), strain 2 (2/4/ 2/0.25; serotype 6B), strain 3 (4/16/4/0.5; serotype 14), and strain 4 (4/16/8/1; serotype 14). Results: Bactericidal activity (≧3 log10 reduction) at 12 and 24 h was obtained against all strains with cefditoren, against strains 1 and 2 with cefuroxime and amoxicillin/clavulanic acid t.i.d., but only against strain 1 with amoxicillin/clavulanic acid b.i.d.. Bactericidal activity at 24 h was related to T > MIC of >30% dosing interval, 1.7–2.0 log10 reductions with T > MIC of 20–30%, and <1 log10 reduction or regrowth with T > MIC of 0%. Conclusions: It is difficult to achieve pharmacodynamic coverage and bactericidal activity by physiological concentrations of oral β-lactams against penicillin-resistant pneumococcal strains exhibiting higher amoxicillin versus penicillin MICs. Cefditoren may offer alternatives.engjournal article1421-9794https://doi.org/10.1159/000118659https://karger.com/che/article/54/2/84/66258/Lactam-Activity-against-Penicillin-Resistantrestricted access611.02Pharmacodynamic simulationStreptococcus pneumoniaeAmoxicillin resistanceBactericidal activityCefditorenCefuroximeAmoxicillin/clavulanic acidMicrobiología médica2414 Microbiología