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Cefuzoname (CZON) one of the aminothiazolyloxyiminoacetamido cephalosporins, was studied for its antibacterial activity, absorption and excretion, concentration in the cerebrospinal fluid (CSF) and the penetration, and clinical efficacy. The following are a summary of the results: 1. Antibacterial activity; The antibacterial activity of CZON was studied on clinically isolated Staphylococcus aureus (cefazolin (CEZ)-susceptible and CEZ-tolerant strains), Escherichia coli, Klebsiella pneumoniae, Proteus mirabilis. Compared with CZON were cefmenoxime (CMX), latamoxef (LMOX), cefoperazone, cefmetazol (CMZ), cefotiam and CEZ, but for S. aureus cefamandole (CMD) was replaced for CPZ. Activities of CZON against S. aureus, both CEZ-susceptible and CEZ-tolerant strains, were superior to those of 6 control drugs. The distribution of MICs for the CEZ-susceptible strains was 0.10-12.5 micrograms/ml, and for the CEZ-tolerant strains 0.20-greater than 100 micrograms/ml. MIC peaks were 0.39 micrograms/ml and 0.78-1.56 micrograms/ml for CEZ-susceptible and CEZ-tolerant strains, respectively. Against both susceptible and tolerant strains, CZON showed superiority to CMZ and CMD, which are used prevalently and used for Methicillin-resistant S. aureus also. Distributions of MICs of CZON (and the peak of MICs) on E. coli, K. pneumoniae, and P. mirabilis were less than or equal to 0.025-1.56 (less than or equal to 0.025), less than or equal to 0.025-25 (less than or equal to 0.025-0.05), less than or equal to 0.025-25 (less than or equal to 0.025) micrograms/ml, respectively, showing CZON's similar antibacterial activity to those of cephalosporins, CMX and LMOX, which are 5th group. 2. Absorption and excretion: Eight patients, aged 10 months to 15 years, were administered with CZON 20 mg/kg, one shot intravenously. Serum concentrations somewhat varied from patient to patient, but the mean value was 48.7 micrograms/ml after 30 minutes of administration which decreased rapidly to 13.3 micrograms/ml after 1 hour, to 3.4 micrograms/ml after 2 hours, to 1.14 micrograms/ml after 4 hours, and to 0.15 microgram/ml after 6 hours. Half-lives were 0.67-1.47 hours, with the mean of 0.87 hour. Urinary recovery rates were 24.7-55.9%, with the mean of 45.1%, in 6 hours after administration. 3. CSF concentration and penetration rate: To 4 pediatric patients with purulent meningitis, CZON 25 mg/kg or 50 mg/kg was administered and the concentration in CSF was measured.(ABSTRACT TRUNCATED AT 400 WORDS)

The in vitro activity of R-3746, an iminomethoxy aminothiazolyl cephalosporin with a CH2OCH3 moiety at position 3, was compared with those of other antibiotics. R-3746 inhibited the majority of hemolytic streptococci (groups A, B, C, F, and G) and Streptococcus pneumoniae at less than 0.06 micrograms/ml, which was comparable to the activity of amoxicillin, 2- to 8-fold more active than cefixime, and 16- to 64-fold more active than cefaclor and cephalexin. Ninety percent of beta-lactamase-producing Haemophilus influenzae and Neisseria gonorrhoeae were inhibited at a concentration 0.25 micrograms/ml, but it was less active against Branhamella spp. It did not inhibit (MIC, greater than 16 micrograms/ml) enterococci, viridans group streptococci, or methicillin-resistant staphylococci. The MICs of R-3746 for 90% of strains tested for Escherichia coli; Klebsiella pneumoniae; Citrobacter diversus; Proteus mirabilis; and Salmonella, Shigella, and Yersinia spp. were less than or equal to 1 micrograms/ml. It was two- to eightfold less active than cefixime but was markedly superior to cefaclor, cephalexin, amoxicillin-clavulanate, and trimethoprimsulfamethoxazole. R-3746 inhibited 50% of Enterobacter cloacae, Enterobacter aerogenes, Citrobacter freundii, Morganella spp., Providencia spp., Proteus vulgaris, and Serratia marcescens at less than or equal to 8 micrograms/ml. Pseudomonas spp. were resistant. Fifty percent of Clostridium spp. were inhibited by 0.5 micrograms/ml, but MICs for Bacteroides spp. were greater than 128 micrograms/ml. R-3746 was not appreciably hydrolyzed by most chromosomal and plasmid-mediated beta-lactamases.

The influence of cefpodoxime proxetil (CPDX-PR, CS-807), a new oral cephalosporin, on the intestinal bacterial flora was studied in tetra-contaminated mice and in pediatric patients. CPDX-PR dry syrup was administered at a dose of 10 mg/kg once a day for 5 consecutive days to mice contaminated with 4 different species of bacteria: Escherichia coli, Enterococcus faecalis, Bacteroides fragilis and Bifidobacterium breve. No notable changes were observed in fecal viable cell counts except that slight decreases of E. coli counts were observed on the days 3 to 5 after starting administration. The subjects in the pediatric study were 5 children with infections, 3 boys and 2 girls at ages from 1 year 1 month to 6 years 10 months, with their body weights ranging from 9.3 to 23.8 kg. CPDX-PR dry syrup was administered at a dose between 3.0 to 3.7 mg/kg, 3 times a day for 4 to 7 days. Although some variations of the fecal bacterial flora were noticed between subjects during the administration of CPDX-PR, no notable changes were observed in major aerobic and anaerobic bacteria such as Enterobacteriaceae, Enterococcus, Bacteroides and Bifidobacterium in 4 of the 5 cases. Large decreases in Streptococcus, Enterobacteriaceae, Bifidobacterium, Eubacterium and anaerobic cocci and an increase in Enterococcus were observed in the other case. There was no case in which glucose non-fermenting Gram-negative rods and fungi became predominant. Regarding Enterobacteriaceae, transitory bacterial replacement was observed within the genus. Fecal concentration of CPDX during the administration of CPDX-PR was extremely low or below the detectable limit except one specimen from a case in which intestinal bacterial flora showed remarkable changes. From the above, CPDX-PR appears to be a drug with a relatively small influence on the intestinal bacterial flora.

Twelve patients with respiratory tract infections were treated with cefpodoxime proxetil (CS-807, CPDX-PR), a new cephem antibiotic. It was given orally at a dose of 200 mg 2 times a day for 4 approximately 15 days. Its clinical effects were evaluated as excellent in 1 case, good in 9 cases and poor in 2 cases. The efficacy rate was 83.3%. Its bacteriological effects were evaluated as eradication in 5 strains and decrement in 1 strain. The eradication rate was 83.3%. No adverse reactions and disorder of laboratory findings due to CPDX-PR were observed.

The kinetic interactions of the beta-lactamase from Enterobacter cloacae 908 R with ceftriaxone, cefotaxime, and ceftazidime have been examined in detail. With all of these cephalosporins, there is an initial rapid reaction involving opening of the beta-lactam that then decreases to a slower steady-state rate (kss) of beta-lactam hydrolysis (at 37 degrees C: ceftriaxone, kss = 0.044 s-1; cefotaxime, kss = 0.033 s-1; ceftazidime, kss = 0.011 s-1). More than stoichiometric quantities of beta-lactam are cleaved during the rapid phase, during which there is accumulation of a transiently stable cephalosporin-enzyme complex whose rate of breakdown is slower than the overall rate of hydrolysis. Qualitatively similar behavior is observed with the E. cloacae M6300 beta-lactamase. These observations eliminate the possibility that the reaction follows a simple linear kinetic scheme. A branched kinetic scheme in which an initially formed acyl intermediate partitions between deacylation and elimination of the 3' substituent is proposed to explain the data. Investigations of the interaction of ceftriaxone with the chromosomally encoded beta-lactamases from Citrobacter freundii, Providencia rettgeri, Morganella morganii, Pseudomonas aeruginosa, and Escherichia coli show that the partitioning behavior of E. cloacae beta-lactamases is atypical. All of the data, however, clearly demonstrate that it is a physical impossibility for cephalosporin trapping to contribute to bacterial resistance phenotypes.