In vitro and in vivo antibacterial activity of T-1982, a new semisynthetic cephamycin antibiotic

In vitro and in vivo antibacterial activities of T-3761, a new quinolone derivative

T-3761, a new quinolone derivative, showed broad and potent antibacterial activity. Its MICs for 90% of the strains tested were 0.20 to 100 micrograms/ml against gram-positive bacteria, including members of the genera Staphylococcus, Streptococcus, and Enterococcus; 0.025 to 3.13 micrograms/ml against gram-negative bacteria, including members of the family Enterobacteriaceae and the genus Haemophilus; 0.05 to 50 micrograms/ml against glucose nonfermenters, including members of the genera Pseudomonas, Xanthomonas, Acinetobacter, Alcaligenes, and Moraxella; 0.025 micrograms/ml against Legionella spp.; and 6.25 to 25 micrograms/ml against anaerobes, including Bacteroides fragilis, Clostridium difficile, and Peptostreptococcus spp. The in vitro activity of T-3761 against these clinical isolates was comparable to or 2- to 32-fold greater than those of ofloxacin and norfloxacin and 2- to 16-fold less and 1- to 8-fold greater than those of ciprofloxacin and tosulfoxacin, respectively. When administered orally, T-3761 showed good efficacy in mice against systemic, pulmonary, and urinary tract infections with gram-positive and gram-negative bacteria, including quinolone-resistant Serratia marcescens and Pseudomonas aeruginosa. The in vivo activity of T-3761 was comparable to or greater than those of ofloxacin, ciprofloxacin, norfloxacin, and tosufloxacin against most infection models in mice. The activities of T-3761 were lower than those of tosufloxacin against gram-positive bacterial systemic and pulmonary infections in mice but not against infections with methicillin-resistant Staphylococcus aureus. The activities of T-3761 against systemic quinolone-resistant Serratia marcescens and Pseudomonas aeruginosa infections in mice were 2- to 14-fold greater than those of the reference agents.

Cefmetazole (CS-1170), a "new" cephamycin with a decade of clinical experience

In vitro and in vivo study results were reviewed from cefmetazole, a "new" parenteral cephamycin. Cefmetazole's spectrum of activity was comparable to that of second-generation cephalosporins, which includes clinical coverage of many Enterobacteriaceae, Staphylococcus spp., streptococci, Haemophilus spp., pathogenic Neisseria, Branhamella catarrhalis, and anaerobic bacteria. Cefmetazole was generally more potent (two- to eightfold) than cefoxitin against organisms within their spectrums and was particularly active for staphylococci (MIC90, 2.0 micrograms/ml). Methicillin-resistant S. aureus strains were more susceptible to cefmetazole alone or in combination (fosfomycin) than any other cephamycin. Cefmetazole has demonstrated excellent stability to aerobic and anaerobic organism-produced beta-lactamases. It also inhibits Type I cephalosporinases and, uniquely, some other cephalosporinases produced by the Bacteroides. This superior stability, enzyme interaction, and better penetration into bacterial cells results in a sustained bactericidal effect and a capacity for more infrequent dosing. The cefmetazole serum elimination half-life was 1.5 hr, also justifying use at greater than or equal to 8-hr intervals. Clinical trials in the United States and Japan demonstrated an acceptably high cefmetazole infection cure rate (88% to 100%), especially in direct comparative studies with cefoxitin. Cefmetazole was also proven very effective in minimizing infectious wound morbidity (prophylaxis) using 2 g single- or multidose regimens. Adverse drug reactions were usually minor; in the Japanese surveillance trial (118,318 patients) the rate was only 2.2% (8.8% in United States). Cefmetazole has been extensively and safely used in Japan since 1980.

Paradoxical antibacterial activity of cefmenoxime against Proteus vulgaris

The growth-inhibitory effect of cefmenoxime against Proteus vulgaris was studied by using the broth dilution and paper disk diffusion methods. Cefmenoxime showed growth-inhibitory activity against Proteus vulgaris at low concentrations but not at high concentrations up to a certain limit. This paradoxical antibacterial activity was not observed with cefoperazone and cefbuperazone. The induction of beta-lactamase by cefmenoxime and the rate of hydrolysis of cefmenoxime in the culture broth were proportional to the initial concentration of this antibiotic. At high initial concentrations, cefmenoxime was rapidly inactivated. On the other hand, neither cefoperazone nor cefbuperazone was inactivated irrespective of concentration. We conclude that cefmenoxime induces beta-lactamase in P. vulgaris, perhaps accounting for its paradoxical antibacterial effect.

Reduction of cephamycin concentrations at the infection site in mice with experimental peritoneal infection caused by cephalosporinase-producing bacteria

In an experimental model of peritoneal infection by cephalosporinase- (Ia and Ic) producing bacteria in mice, the reduction of cefoxitin, cefmetazole, and cefazolin concentrations in peritoneal fluid was observed in the mice infected with the Ia enzyme producer, whereas cefbuperazone concentrations were not reduced.

Cephamycin inactivation due to enzymatic hydrolysis by beta-lactamase from Bacteroides fragilis

The susceptibility of 53 clinical isolates of Bacteroides fragilis to cephamycins was examined. Judging from the MICs for 50% of the strains tested, moxalactam was the most active, however, judging from the MICs for 90% of the strains tested, cefbuperazone was more effective than moxalactam. A correlation was observed between in vitro activity of benzylpenicillin and cephaloridine and beta-lactamase production. Inactivation due to enzymatic hydrolysis of cephamycins over a short time was not observed; however, inactivation was detected by a double disk diffusion test, and moxalactam was most easily inactivated. We conclude that inactivation due to enzymatic hydrolysis of cephamycins over a long time may play an important role in resistance to some cephamycins in strains of B. fragilis.

Pharmacokinetics of cefmetazole administered intramuscularly and intravenously to healthy adults

The pharmacokinetics of cefmetazole, a new parenteral cephalosporin, administered intravenously and intramuscularly at a dose of 30 mg/kg to two groups of seven healthy volunteers were studied. Concentrations in serum were monitored over 8 h by a high-pressure liquid chromatography technique. The plasma concentration-time data were statistically fitted to a biexponential equation for both administration routes, and the data were analyzed by a two- and one-compartment kinetic model, respectively. For the dose range and the administration routes used, the pharmacokinetics of cefmetazole proved to be essentially linear, with clearances from plasma ranging between 3.8 and 12.5 liters/h. The mean maximum concentration in plasma after intramuscular administration of the drug was 90.1 micrograms/ml at 0.7 h. The elimination half-life, about 1.3 h, did not show statistically significant differences for the two routes of administration studied.

In vitro activity of cefbuperazone against Bacteroides spp

The activity of cefbuperazone was tested in vitro against 287 clinical isolates of Bacteroides spp. Cefbuperazone showed good activity against B. fragilis, B. vulgatus, and other Bacteroides species, comparable to that of cefoxitin. It was relatively ineffective against B. distasonis and the B. thetaiotaomicron-ovatus group and was not active against cefoxitin-resistant Bacteroides spp.

In vitro activity of cefbuperazone and other antimicrobial agents against isolates from the female genital tract

Cefbuperazone (BMY 25182), a new cephamycin, showed activity similar to those of moxalactam and other cephalosporin-cephamycins against aerobic and anaerobic bacteria from female genital tract infections. MICs of the antimicrobial agents were less than or equal to 16 micrograms/ml for greater than 97% of organisms tested. All of the anaerobic bacteria tested were susceptible to clindamycin, metronidazole, and chloramphenicol.

BMY28142, cefbuperazone (T-1982), and Sch 34343. Antimicrobial activity against 94 anaerobes compared to seven other antimicrobial agents

Three new beta-lactams were evaluated against 94 anaerobic strains representing 15 species using a Wilkins-Chalgren broth microdilution method. The penems, Sch 29482 and Sch 34343, were most active with all minimum inhibitory concentrations (MICs) at less than or equal to 4.0 micrograms/ml and MIC90s of less than or equal to 0.25 micrograms/ml. BMY 28142 had a more limited antianaerobic activity against Bacteroides fragilis with a MIC50 and MIC90 of 32 and 128 micrograms/ml, respectively. Cefbuperazone (T-1982) had low B. fragilis MICs (MIC90, 8.0 micrograms/ml), but potentially resistant range MIC90 results for the other species in the B. fragilis group and Clostridium species.

In vitro activity of Sch 34343 and cefbuperazone against anaerobic bacteria

The in vitro activities of Sch 34343, a new penem antibiotic, and cefbuperazone, a new cephamycin antibiotic, were determined against 459 clinical anaerobic bacterial isolates and compared with the activities of imipenem and cefoxitin, respectively, by an agar dilution method. Both penems showed potent and similar activity against all anaerobic bacteria tested, particularly Peptococcus spp., Bacteroides fragilis, and Clostridium perfringens. All organisms except a single strain of Fusobacterium necrogenes were inhibited by an 8 micrograms/ml concentration of either Sch 34343 or imipenem. Overall, gram-positive bacilli, particularly Lactobacillus species, Clostridium difficile, and Bifidobacterium and Actinomyces species, were relatively more resistant to either penem than other genera of anaerobic bacteria tested. Cefbuperazone demonstrated only modest activity against a wide spectrum of anaerobic bacteria. It had excellent and selective activity against B. fragilis and Bacteroides vulgatus but was highly inactive against Bacteroides distasonis and Bacteroides thetaiotaomicron within the B. fragilis group. Both cephamycins showed virtually no activity against C. difficile and Lactobacillus spp. Although cefbuperazone was more active against Bifidobacterium spp., it had less activity against Fusobacterium spp., Eubacterium spp., and all Bacteroides spp. other than B. fragilis and B. vulgatus.

In vitro activity of cefbuperazone compared with that of other new beta-lactam agents against anaerobic gram-negative bacilli and contribution of beta-lactamase to resistance

Cefbuperazone was compared with other currently available and investigational antibiotics against 278 clinical isolates of anaerobic gram-negative bacilli by an agar dilution method. Cefbuperazone and cefotetan were equally active against Bacteroides fragilis, with 8% of the organisms tested found to be resistant to 32 micrograms of either drug per ml. Cefoperazone, cefotaxime, ceftriaxone, and cefmetazole were less active against these strains; cefoxitin, moxalactam, piperacillin, clindamycin, and metronidazole were more active. None of the agents were consistently active against any of the other anaerobic gram-negative bacilli except imipenem, for which the minimum concentration required to inhibit 90% of all strains tested was 4 micrograms/ml. A 10,000-fold increase in inoculum size caused an increase in the MIC of ceftriaxone, cefotaxime, and cefoperazone but not of cefbuperazone, cefotetan, or cefoxitin. Investigation of the mechanism of resistance to cephalosporin-like agents demonstrated a correlation between the level of resistance and beta-lactamase activity. Cefbuperazone, cefotetan, and cefoxitin were not hydrolyzed, had lower MICs, and were less affected by changes in inoculum size than were cefotaxime, ceftriaxone, and cefoperazone.

Antimicrobial activities of BMY-28142, cefbuperazone, and cefpiramide compared with those of other cephalosporins

The antimicrobial activities of BMY-28142, cefbuperazone (BMY-25182; formerly T-1982), and cefpiramide (WY-44635; formerly SM-1652) were compared with those of cefmenoxime, cefoperazone, cefotaxime, ceftizoxime, and moxalactam. BMY-28142 was the most active cephalosporin against the majority of aerobic and facultatively anaerobic microorganisms studied. Its spectrum of activity was very similar to that of cefotaxime. However, BMY-28142, cefbuperazone, cefmenoxime, cefotaxime, ceftizoxime, and moxalactam were equivalent in activity and rate of killing against members of the family Enterobacteriaceae. Cefpiramide was considerably less active than the other cephalosporins against the Enterobacteriaceae.

Comparative in vitro activity of cefbuperazone against anaerobic bacteria isolated from community hospitals

The activity of cefbuperazone against 266 strains of anaerobic bacteria was determined by the agar dilution method and compared with cefoxitin, moxalactam, piperacillin, and clindamycin. All strains were recent clinical isolates from community hospitals. All agents tested showed good activity against Bacteroides fragilis, Fusobacterium spp., Propionibacterium spp., Clostridium septicum, Clostridium perfringens, and the anaerobic, gram-positive cocci and gram-negative cocci. Cefbuperazone, cefoxitin, and moxalactam had poor activity against Bacteroides thetaiotaomicron, Bacteroides ovatus, and Bacteroides distasonis. The susceptibility of other Clostridium spp., Lactobacillus spp., and Eubacterium lentum was variable. Our community hospital isolates showed a difference in susceptibility patterns from those reported from university and research centers. This supports the recommendation that clinical microbiology laboratories, including those in community hospitals, need to perform susceptibility testing on representative clinical isolates.

Susceptibilities of 45 clinical isolates of Proteus penneri

Patterns of susceptibility of 45 Proteus penneri clinical isolates to 14 antimicrobial agents were evaluated by a macrobroth dilution method. All strains were highly susceptible to ceftizoxime, ceftazidime, moxalactam, cefoxitin, gentamicin, tobramycin, netilmicin, and, with few exceptions, to amikacin, piperacillin, and cefoperazone. Most strains were susceptible to cefotaxime and ceftriaxone. All strains were resistant to cefazolin and cefsulodin.

Properties of novel beta-lactamase produced by Bacteroides fragilis

Bacteroides fragilis strains were isolated from clinical specimens. B. fragilis G-237 was highly resistant to beta-lactam antibiotics due to beta-lactamase production. The purified enzyme from this strain gave a single protein band on polyacrylamide gel electrophoresis. The isoelectric point was 4.8, and the molecular weight was estimated to be 26,000 by sodium dodecyl sulfate-polyacrylamide gel electrophoresis. The enzyme activity was inhibited by p-chloromercuribenzoate and iodine but not by clavulanic acid or sulbactam. The purified enzyme showed a unique substrate profile by hydrolyzing at a high rate most of the cephalosporins, including cephamycin derivatives, penicillins, and imipenem (formerly imipemide, N-formimidoyl thienamycin, or MK 0787).