title: Efficacy of beta-lactams against experimental pneumococcal endocarditis caused by strains with different susceptibilities to penicillin.
abstract: OBJECTIVE
  To compare the in vitro and in vivo activity of penicillin, cefotaxime and ceftriaxone, using three strains of Streptococcus pneumoniae with different susceptibilities to penicillin (MICs of 0.015, 0.25 and 2 mg/L, respectively).
  
  
  METHODS
  Time-kill curves and an experimental model of endocarditis in rabbits.
  
  
  RESULTS
  Penicillin was efficacious in clearing bacteria from vegetations and blood irrespective of whether infections were caused by penicillin-susceptible or penicillin-resistant strains (P < 0.01 with respect to control groups). The same efficacy was shown with cefotaxime and ceftriaxone. Comparing the results of the in vivo model with those obtained in time-kill curves, penicillin showed the best results.
  
  
  CONCLUSIONS
  These results confirm that penicillin is efficacious in the treatment of pneumococcal infections, including those produced by strains with MICs < or = 2 mg/L (with the exception of pneumococcal meningitis). These results also suggest that the breakpoints to define susceptibility and resistance of S. pneumoniae to penicillin must be reviewed, as has been done with amoxicillin and third-generation cephalosporins.
authors.affiliation: Infectious Diseases Service, Virgen del Rocío University Hospitals, Sevilla, Spain. cristina.pichardo.exts@juntadeandalucia.es
authors.forename: Cristina
authors.initials: C
authors.lastname: Pichardo
authors.forename: Fernando
authors.initials: F
authors.lastname: Docobo-Pérez
authors.forename: Maria E
authors.initials: ME
authors.lastname: Pachón-Ibáñez
authors.forename: Manuel E
authors.initials: ME
authors.lastname: Jiménez-Mejías
authors.forename: Andrés
authors.initials: A
authors.lastname: García-Curiel
authors.forename: F Javier
authors.initials: FJ
authors.lastname: Caballero-Granado
authors.forename: Ignacio
authors.initials: I
authors.lastname: Moreno-Maqueda
authors.forename: Jerónimo
authors.initials: J
authors.lastname: Pachón
mesh_terms: D000818:Animals; D000900:Anti-Bacterial Agents / Q000097:blood / Q000493:pharmacokinetics / Q000627:therapeutic use*; D002439:Cefotaxime / Q000097:blood / Q000493:pharmacokinetics / Q000494:pharmacology / Q000627:therapeutic use; D002443:Ceftriaxone / Q000097:blood / Q000493:pharmacokinetics / Q000494:pharmacology / Q000627:therapeutic use; D004697:Endocarditis, Bacterial / Q000150:complications / Q000188:drug therapy* / Q000382:microbiology*; D006207:Half-Life; D008826:Microbial Sensitivity Tests; D010403:Penicillin Resistance; D010406:Penicillins / Q000097:blood / Q000493:pharmacokinetics / Q000494:pharmacology / Q000627:therapeutic use; D011008:Pneumococcal Infections / Q000150:complications / Q000188:drug therapy* / Q000382:microbiology; D011817:Rabbits; D013296:Streptococcus pneumoniae / Q000145:classification / Q000187:drug effects* / Q000502:physiology; D047090:beta-Lactams / Q000097:blood / Q000493:pharmacokinetics / Q000494:pharmacology / Q000627:therapeutic use*
chemical_list: D000900:Anti-Bacterial Agents; D010406:Penicillins; D047090:beta-Lactams; D002443:Ceftriaxone; D002439:Cefotaxime