Efficacy of beta-lactams against experimental pneumococcal endocarditis caused by strains with different susceptibilities to penicillin.
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.
Pichardo
Cristina
C
Infectious Diseases Service, Virgen del Rocío University Hospitals, Sevilla, Spain. cristina.pichardo.exts@juntadeandalucia.es
Docobo-Pérez
Fernando
F
Pachón-Ibáñez
Maria E
ME
Jiménez-Mejías
Manuel E
ME
García-Curiel
Andrés
A
Caballero-Granado
F Javier
FJ
Moreno-Maqueda
Ignacio
I
Pachón
Jerónimo
J
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*
D000900:Anti-Bacterial Agents; D010406:Penicillins; D047090:beta-Lactams; D002443:Ceftriaxone; D002439:Cefotaxime