In vitro activity of ceftizoxime,ceftazidime, cefuroxime,ceftriaxone, cefotaxime,and penicillin againstStreptococcus pneumoniae as determined by three quantitative methods

E-test, broth microdilution, and agar dilution susceptibility tests were used to evaluate penicillin and five extended-spectrum cephalosporins against 196 strains ofStreptococcus pneumoniae with different levels of penicillin resistance. Oxacillin disk tests corresponded to minimum inhibitory concentrations of penicillin determined by the E-test better than those generated by broth microdilution or agar dilution methods. Relative potency of the study drugs was as follows: cefotaxime=ceftriaxone > penicillin > cefuroxime > ceftizoxime > ceftazidime.