In Vitro Antimicrobial Activity of L-105 and Its Therapeutic Efficacy on Lower Respiratory Infections

In vitro antimicrobial activity of L-105, a novel cephem for parenteral use, was examined by a broth dilution method using the Dynatech MIC 2000 system, and its therapeutic effects on lower respiratory infections were evaluated. The minimum inhibitory concentrations (MICs) and minimum bactericidal concentrations (MBCs) of L-105, latamoxef (LMOX = moxalactam), ceftizoxime (CZX), cefmenoxime (CMX), cefmetazole (CMZ), cefazolin (CEZ) and ampicillin (ABPC) against 239 clinical isolates consisting of ten species were determined. L-105 was more highly active against S. aureus, S. pyogenes and H. influenzae than were any other antibiotics. L-105 was almost as active as cefazolin against S. epidermidis, and as active as ceftizoxime or cefmenoxime against S. pneumoniae and Enterobacteriaceae. L-105 was as active as latamoxef against P. aeruginosa. The values of MBCs of L-105 against a wide variety of pathogens was found to be very close to those of MICs. A daily dose of 2 to 3 grams of L-105 was given by drip infusion to a total of 35 cases which consisted of 25 patients with pneumonia, five patients with lung abscess, three patients with infection in association with lung cancer and one patient each with diffuse panbronchiolitis and infection in association with pulmonary tuberculosis. The clinical effects were excellent in eight patients, good in 15, fair in three and poor in three patients. Six patients with Mycoplasma pneumoniae pneumonia were excluded from clinical evaluation. Eighteen strains were identified as causative organisms. However, as to 2 out of these 18, strains further bacteriological documents were not available for evaluation. Twelve of the remaining 16 strains were eradicated by the treatment with L-105. Three strains were markedly deminished in number, however one strain persisted. Drug exanthema and drug fever were observed in one patient each. An elevation of values of serum transaminase was observed in seven patients. An elevation of values of LDH, leucocytopenia and eosinophilia were observed in one patient each. These adverse reactions disappeared after completion of the therapy with L-105. From the above results, it was concluded that L-105 is one of the most useful antibiotics for the treatment of lower respiratory infections.