Time-kill studies of antimicrobial combinations including cefotaxime, ceftriaxone, vancomycin and meropenem against cephalosporin-resistant Streptococcus pneumoniae

Background: Resistance of Streptococcus pneumoniae to penicillin is now wid espread and rapidly increasing all over the world. This has led to the crit ical need for alternative antimicrobial therapy. Methods: To assess the act ivities of antimicrobial combinations, including cefotaxime, ceftriaxone, v ancomycin and meropenem, time-kill studies were conducted against five stra ins of penicillin- and cephalosporin-resistant S. pneumoniae at clinically achievable antimicrobial concentrations in cerebrospinal fluid. Results: Co mbinations of an extended-spectrum cephalosporin with vancomycin were not s ynergistic. Meropenem had a comparable bactericidal activity to those combi nations, and its killing activity was not affected by the addition of cefot axime, ceftriaxone or vancomycin. Conclusions: It is suggested that meropen em could be an effective alternative for the treatment of penicillin- and c ephalosporin-resistant pneumococcal meningitis. However, more clinical data are required before it can be recommended as an effective antimicrobial ag ent for such cases. Copyright (C) 2000 S. Karger AG, Basel.