Cefoxitin and cephamycins: microbiological studies.

The cephamycins are a family of beta-lactam antibiotics that are produced by actinomycetes and are structurally similar to the cephalosporins. They are characterized by the presence of a 7-alpha-methoxyl group, which confers unusually high resistance to beta-lactamases. Cefoxitin, the first semisynthetic cephamycin, is resistant to almost all beta-lactamases. Cefoxitin retains the 3-carbamoyl group of cephamycin C and thus has excellent metabolic stability. Cefoxitin is bactericidal and almost devoid of any inoculum effect. Active against many cephalothin-resistant gram-negative bacteria, cefoxitin demonstrates a very broad spectrum that includes indole-positive Proteus and many strains of Serratia. In contrast to that of the cephalosporins, cefoxitin's spectrum of activity against anaerobic pathogens includes Bacteroides fragilis. The therapeutic effectiveness of cefoxitin in experimental infections in mice confirms the excellent characteristics of this semisynthetic cephamycin and indicates that it should be a very valuable agent for treatment of bacterial infections.