A study of susceptibility of 100 clinical isolates belonging to the Streptococcus milleri group to 16 cephalosporins

The Streptococcus milleri group are uniformly susceptible to penicillin G, but their susceptibilities to different cephalosporins vary considerably. T he antimicrobial susceptibilities of 100 clinically significant strains of the S. milleri group to 16 cephalosporins were determined by the agar dilut ion method. The majority of first-generation cephalosporins were highly act ive. Cefamandole, cefuroxime and cefprozil were the most active second-gene ration agents examined. Third-generation parenteral cephalosporins exhibite d excellent activity, with the exception of ceftazidime. The most active of the oral preparations of this group was cefpodoxime, with cefixime and cef tibuten being considerably less active. MICs of cefepime, the only fourth-g eneration cephalosporin tested, were higher than those of cefotaxime and ce ftriaxone.