%0 Journal Article
%A Alou Cervera, Luis
%A Giménez, María José
%A Sevillano Fernández, David
%A Aguilar, Lorenzo
%A Cafini, Fabio
%A Echeverría, Olatz
%A Pérez Trallero, Emilio
%A Prieto Prieto, José
%T A pharmacodynamic approach to antimicrobial activity in serum and epithelial lining fluid against in vivo-selected Streptococcus pneumoniae mutants and association with clinical failure in pneumonia
%D 2006
%@ 0305-7453
%U https://hdl.handle.net/20.500.14352/107175
%X Objectives: Emergence of resistance may be prevented by killing both the parental infecting strain and subsequent less susceptible step-mutants. The present study analyses eradication and resistance selection in Streptococcus pneumoniae with moxifloxacin, levofloxacin and azithromycin, using a parental serotype 3 clinical strain (strain A) and its correspondent step-mutant derivatives resistant to these antibiotics (B, C, D), which were selected in vivo in a patient with pneumonia.Methods: Moxifloxacin, levofloxacin and azithromycin MICs were 1, 2 and 0.5 mg/L for the parental strain; 4, 16 and 4 mg/L for isolate B; and 4, 16 and >128 mg/L for isolates C and D, respectively. A pharmacokinetic computerized device was used to simulate serum and epithelial lining fluid (ELF) concentrations. Initial inoculum was approximately 10(8) cfu/mL. Population analysis profiles were performed using plates with increasing antimicrobial concentrations.Results: In ELF simulations, moxifloxacin showed a bactericidal pattern against all isolates with a minority (approximately 100 cfu/mL) of the surviving population (isolates B, C and D) growing on plates with moxifloxacin concentrations just above those in ELF. Levofloxacin and azithromycin showed a bactericidal pattern only against isolate A, with the whole population of isolates B, C and D growing on plates with levofloxacin concentrations higher (16-64 mg/L) than those in ELF and in plates with azithromycin concentrations as high as 2048 mg/L (for isolates C and D).Conclusions: Antimicrobial activity in pulmonary tissue against possible emerging resistant mutants during pneumonia treatment may prevent failures more than the solely activity against the S. pneumoniae parental infecting strain.
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