In vitro antimicrobial activity of MT-141 and its therapeutic efficacy in respiratory tract infections

In vitro antimicrobial activity of MT-141, a new derivative of cephamycin, was examined by a broth dilution method with Dynatech MIC 2000 system. Also, the therapeutic efficacy of MT-141 was evaluated in patients with respiratory tract infections. The minimum inhibitory concentrations (MICs) of MT-141 against the following 120 strains of clinical isolates were compared with those of cefmetazole (CMZ), cefotiam (CTM), cefoperazone (CPZ),and ceftizoxime (CZX) against each 20 strains of S. aureus, E. coli, K. pneumoniae, S. marcescens, E. cloacae and P. aeruginosa. Against S. aureus, MT-141 was shown to be less active than CMZ, CPZ and CZX. In contrast, MT-141 was far more active than CMZ, although less active than CZX, against E. coli and K. pneumoniae, and more active than CMZ and CTM against S. marcescens and E. cloacae. But, MT-141 was almost inactive against P. aeruginosa. Ten patients suffering from respiratory tract infections were treated with intravenous drip infusion of MT-141 at the dose of one gram twice a day. The response to the treatment with MT-141 was good in eight patients and poor in the other two. Undesirable symptoms were not observed, but abnormal laboratory findings such as a slight elevation of GOT, a mild thrombocytopenia with mild anemia and an eosinophilia were observed during or after the administration of MT-141.