Flomoxef and cefazolin had nearly the same activity against staphylococci, which was stronger than that of other cephalosporins. Against Streptococcus pyogenes, Streptococcus agalactiae and Streptococcus pneumoniae, cefotaxime and cefazolin were more active than flomoxef, but the other cephamycins were less active than flomoxef. In comparison to the other cephalosporins, latamoxef and flomoxef had higher activity against Branhamella catarrhalis, whereas cefotaxime, latamoxef and cefotetan were more active against Haemophilus influenzae. Flomoxef was the only drug exhibiting activity against Clostridium difficile. The activity of flomoxef and latamoxef against Bacteroides fragilis was stronger than that of the other cephalosporins, but Bacteroides bivius was resistant to each of these antibiotics.