In vitro antimicrobial activity and therapeutic efficacy of FK037 in the treatment of respiratory tract infections

The in vitro antimicrobial activities of FK037, a novel parenteral cephalosporin developed in Japan, and its therapeutic efficacy were evaluated in the treatment of respiratory tract infections. The minimum inhibitory concentrations (MICs) of FK037, cefpirome (CPR), ceftazidime (CAZ) and flomoxef (FMOX) against a total of 138 strains consisting of six different species, methicillinsusceptible Staphylococcus aureus (MSSA), methicillin-resistant Staphylococcus aureus (MRSA), Escherichia coil, Klebsiella pneumoniae, Enterobacter cloacae, Serratia marcescens and Pseudomonas aeruginosa were determined by the micro-broth dilution method using the Dynatech MIC 2000 system. As shown in MICs, FK037 was more active than CAZ and FMOX, and as active as CPR against most of the species tested. Growth of all the MRSA strains tested was inhibited by 64 μg/ml or less of FK037. A dose of 1 g (7 patients), 2 g (6 patients) and 4 g (5 patients), respectively, of FK037 was given daily to a total of 18 patients for 6 to 15 days (mean: 11.2 days): 13 with pneumonia, one with pyothorax, and 2 each with secondary infection in association with bronchiectasis and chronic bronchitis. The clinical effects were excellent in 9 and good in 8 (efficacy rate: 100%). One patient with eosinophilic pneumonia was excluded from clinical evaluation. Seven strains were identified as causative organisms: 4 strains of Streptococcus pneumoniae, 2 strains of Heamophilus influenzae, and one strain of Moraxella catarrhalis. FK037 eradicated all of them. No clinical adverse effects were observed during treatment with FK037. A transient elevation of γ-GTP and leucocytopenia was observed in one patient each. From the above results, we conclude that FK037 is a useful antibiotic for parenteral use as a first choice in the treatment of respiratory tract infections.