Alou Cervera, LuisGiménez, María JoséSevillano Fernández, DavidAguilar, LorenzoCafini, FabioEcheverría, OlatzPérez Trallero, EmilioPrieto Prieto, José2024-07-292024-07-292006-05-30Alou L, Giménez MJ, Sevillano D, Aguilar L, Cafini F, Echeverría O, Pérez-Trallero E, Prieto J. 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. J Antimicrob Chemother. 2006 Aug;58(2):349-58.0305-745310.1093/jac/dkl250https://hdl.handle.net/20.500.14352/107175Objectives: 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.engjournal article1460-2091https://doi.org/10.1093/jac/dkl250https://academic.oup.com/jac/article/58/2/349/722063restricted access611.02moxifloxacinlevofloxacinazithromycinpharmacodynamicsMicrobiología médica2414 Microbiología